Re: [PATCH 2.6.16.29 1/1] memory: enhance Linux swap subsystem

From: Pavel Machek
Date: Fri Dec 29 2006 - 04:29:28 EST

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On Fri 2006-12-29 14:45:33, yunfeng zhang wrote:
> I've re-published my work on quilt, sorry.

Your patch is still wordwrapped.

Do not cc linus on non-final version of the patch.

Patch should be against latest kernel.

Patch should have changelog and signed off by.

Why the change? Do you gain 5% on kernel compile on 20MB box?

Pavel

>
> Index: linux-2.6.16.29/Documentation/vm_pps.txt
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ linux-2.6.16.29/Documentation/vm_pps.txt 2006-12-29
> 14:36:36.507332384 +0800
> @@ -0,0 +1,192 @@
> + Pure Private Page System (pps)
> + Copyright by Yunfeng Zhang on GFDL 1.2
> + zyf.zeroos@xxxxxxxxx
> + December 24-26, 2006
> +
> +// Purpose <([{
> +The file is used to document the idea which is published firstly at
> +http://www.ussg.iu.edu/hypermail/linux/kernel/0607.2/0451.html, as a part
> of my
> +OS -- main page http://blog.chinaunix.net/u/21764/index.php. In brief, a
> patch
> +of the document to enchance the performance of Linux swap subsystem. You
> can
> +find the overview of the idea in section <How to Reclaim Pages more
> +Efficiently> and how I patch it into Linux 2.6.16.29 in section <Pure
> Private
> +Page System -- pps>.
> +// }])>
> +
> +// How to Reclaim Pages more Efficiently <([{
> +Good idea originates from overall design and management ability, when you
> look
> +down from a manager view, you will relief yourself from disordered code and
> +find some problem immediately.
> +
> +OK! to modern OS, its memory subsystem can be divided into three layers
> +1) Space layer (InodeSpace, UserSpace and CoreSpace).
> +2) VMA layer (PrivateVMA and SharedVMA, memory architecture-independent
> layer).
> +3) PTE and page layer (architecture-dependent).
> +
> +Since the 2nd layer assembles the much statistic of page-acess
> information, so
> +it's nature that swap subsystem should be deployed and implemented on the
> 2nd
> +layer.
> +
> +Undoubtedly, there are some virtues about it
> +1) SwapDaemon can collect the statistic of process acessing pages and by it
> + unmaps ptes, SMP specially benefits from it for we can use
> flush_tlb_range
> + to unmap ptes batchly rather than frequently TLB IPI interrupt per a
> page in
> + current Linux legacy swap subsystem.
> +2) Page-fault can issue better readahead requests since history data shows
> all
> + related pages have conglomerating affinity. In contrast, Linux
> page-fault
> + readaheads the pages relative to the SwapSpace position of current
> + page-fault page.
> +3) It's conformable to POSIX madvise API family.
> +
> +Unfortunately, Linux 2.6.16.29 swap subsystem is based on the 3rd layer --
> a
> +system on zone::active_list/inactive_list.
> +
> +I've finished a patch, see section <Pure Private Page System -- pps>.
> Note, it ISN'T perfect.
> +// }])>
> +
> +// Pure Private Page System -- pps <([{
> +As I've referred in previous section, perfectly applying my idea need to
> unroot
> +page-surrounging swap subsystem to migrate it on VMA, but a huge gap has
> +defeated me -- active_list and inactive_list. In fact, you can find
> +lru_add_active code anywhere ... It's IMPOSSIBLE to me to complete it only
> by
> +myself. It's also the difference between my design and Linux, in my OS,
> page is
> +the charge of its new owner totally, however, to Linux, page management
> system
> +is still tracing it by PG_active flag.
> +
> +So I conceive another solution:) That is, set up an independent
> page-recycle
> +system rooted on Linux legacy page system -- pps, intercept all private
> pages
> +belonging to PrivateVMA to pps, then use my pps to cycle them. By the
> way, the
> +whole job should be consist of two parts, here is the first --
> +PrivateVMA-oriented (PPS), other is SharedVMA-oriented (should be called
> SPS)
> +scheduled in future. Of course, if all are done, it will empty Linux legacy
> +page system.
> +
> +In fact, pps is centered on how to better collect and unmap process private
> +pages in SwapDaemon mm/vmscan.c:shrink_private_vma, the whole process is
> +divided into six stages -- <Stage Definition>. Other sections show the
> remain
> +aspects of pps
> +1) <Data Definition> is basic data definition.
> +2) <Concurrent racers of Shrinking pps> is focused on synchronization.
> +3) <Private Page Lifecycle of pps> -- how private pages enter in/go off
> pps.
> +4) <VMA Lifecycle of pps> which VMA is belonging to pps.
> +
> +PPS uses init_mm.mm_list list to enumerate all swappable UserSpace.
> +
> +I'm also glad to highlight my a new idea -- dftlb which is described in
> +section <Delay to Flush TLB>.
> +// }])>
> +
> +// Delay to Flush TLB (dftlb) <([{
> +Delay to flush TLB is instroduced by me to enhance flushing TLB
> efficiency, in
> +brief, when we want to unmap a page from the page table of a process, why
> we
> +send TLB IPI to other CPUs immediately, since every CPU has timer
> interrupt, we
> +can insert flushing tasks into timer interrupt route to implement a
> +free-charged TLB flushing.
> +
> +The trick is implemented in
> +1) TLB flushing task is added in fill_in_tlb_task of mm/vmscan.c.
> +2) timer_flush_tlb_tasks of kernel/timer.c is used by other CPUs to execute
> + flushing tasks.
> +3) all data are defined in include/linux/mm.h.
> +
> +The restriction of dftlb. Following conditions must be met
> +1) atomic cmpxchg instruction.
> +2) atomically set the access bit after they touch a pte firstly.
> +3) To some architectures, vma parameter of flush_tlb_range is maybe
> important,
> + if it's true, since it's possible that the vma of a TLB flushing task
> has
> + gone when a CPU starts to execute the task in timer interrupt, so don't
> use
> + dftlb.
> +combine stage 1 with stage 2, and send IPI immediately in
> fill_in_tlb_tasks.
> +// }])>
> +
> +// Stage Definition <([{
> +The whole process of private page page-out is divided into six stages, as
> +showed in shrink_pvma_scan_ptes of mm/vmscan.c
> +1) PTE to untouched PTE (access bit is cleared), append flushing
> tasks to dftlb.
> +2) Convert untouched PTE to UnmappedPTE.
> +3) Link SwapEntry to every UnmappedPTE.
> +4) Synchronize the page of a UnmappedPTE with its physical swap page.
> +5) Reclaimed the page and shift UnmappedPTE to SwappedPTE.
> +6) SwappedPTE stage.
> +// }])>
> +
> +// Data Definition <([{
> +New VMA flag (VM_PURE_PRIVATE) is appended into VMA in include/linux/mm.h.
> +
> +New PTE type (UnmappedPTE) is appended into PTE system in
> +include/asm-i386/pgtable.h.
> +// }])>
> +
> +// Concurrent Racers of Shrinking pps <([{
> +shrink_private_vma of mm/vmscan.c uses init_mm.mmlist to scan all swappable
> +mm_struct instances, during the process of scaning and reclaiming process,
> it
> +readlockes every mm_struct object, which brings some potential concurrent
> +racers
> +1) mm/swapfile.c pps_swapoff (swapoff API).
> +2) mm/memory.c do_wp_page, handle_pte_fault::unmapped_pte,
> do_anonymous_page
> + (page-fault).
> +// }])>
> +
> +// Private Page Lifecycle of pps <([{
> +All pages belonging to pps are called as pure private page.
> +
> +IN (NOTE, when a pure private page enters into pps, it's also trimmed from
> +Linux legacy page system by commeting lru_cache_add_active clause)
> +1) fs/exec.c install_arg_pages (argument pages).
> +2) mm/memory do_anonymous_page, do_wp_page, do_swap_page (page fault).
> +3) mm/swap_state.c read_swap_cache_async (swap pages).
> +
> +OUT
> +1) mm/vmscan.c shrink_pvma_scan_ptes (stage 6, reclaim a private page).
> +2) mm/memory zap_pte_range (free a page).
> +3) kernel/fork.c dup_mmap (if someone uses fork, migrate all
> pps pages
> + back to let Linux legacy page system manage them).
> +
> +When a pure private page is in pps, it can be visited simultaneously by
> +page-fault and SwapDaemon.
> +// }])>
> +
> +// VMA Lifecycle of pps <([{
> +When a PrivateVMA enters into pps, it's or-ed a new flag --
> VM_PURE_PRIVATE,
> +the flag is used in the shrink_private_vma of mm/vmscan.c. Other fields
> are
> +left untouched.
> +
> +IN.
> +1) fs/exec.c setup_arg_pages (StackVMA).
> +2) mm/mmap.c do_mmap_pgoff, do_brk (DataVMA).
> +3) mm/mmap.c split_vma, copy_vma (in some cases, we need copy a VMA
> from an
> + exist VMA).
> +
> +OUT.
> +1) kernel/fork.c dup_mmap (if someone uses fork, return the
> vma back to
> + Linux legacy system).
> +2) mm/mmap.c remove_vma, vma_adjust (destroy VMA).
> +3) mm/mmap.c do_mmap_pgoff (delete VMA when some errors occur).
> +// }])>
> +
> +// Postscript <([{
> +Note, some circumstances aren't tested due to hardware restriction e.g. SMP
> +dftlb.
> +
> +Here are some improvements about pps
> +1) In fact, I recommend one-to-one private model -- PrivateVMA, (PTE,
> + UnmappedPTE) and PrivatePage (SwapPage) which is described in my OS and
> the
> + aboved hyperlink of Linux kernel mail list. So it's a compromise to use
> + Linux legacy SwapCache in my pps.
> +2) SwapCache should provide more flexible interfaces, shrink_pvma_scan_ptes
> + need allocate swap entries in batch, exactly, allocate a batch of fake
> + continual swap entries, see mm/pps_swapin_readahead.
> +3) pps statistic entry in /proc/meminfo.
> +4) a better arithmetic to pick mm out to scan and shrink in
> shrink_private_vma.
> +5) It's better to execute the first 2 stages when system is idle, current
> + SwapDaemon only is activated when free pages are low.
> +6) A scanning count should be added into mm_struct, so when the count is
> + becoming enough old to open stage 3 and 4.
> +
> +I'm still working on improvement 4, 5 and 6 to find out how to maximum the
> +performance of swap subsystem.
> +
> +If Linux kernel group can't make a schedule to re-write their memory code,
> +however, pps maybe is the best solution until now.
> +// }])>
> +// vim: foldmarker=<([{,}])> foldmethod=marker et
> Index: linux-2.6.16.29/fs/exec.c
> ===================================================================
> --- linux-2.6.16.29.orig/fs/exec.c 2006-12-29 13:56:51.000000000 +0800
> +++ linux-2.6.16.29/fs/exec.c 2006-12-29 13:57:18.000000000 +0800
> @@ -321,7 +321,6 @@
> goto out;
> }
> inc_mm_counter(mm, anon_rss);
> - lru_cache_add_active(page);
> set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
> page, vma->vm_page_prot))));
> page_add_new_anon_rmap(page, vma, address);
> @@ -436,6 +435,7 @@
> kmem_cache_free(vm_area_cachep, mpnt);
> return ret;
> }
> + enter_pps(mm, mpnt);
> mm->stack_vm = mm->total_vm = vma_pages(mpnt);
> }
>
> Index: linux-2.6.16.29/include/asm-i386/pgtable-2level.h
> ===================================================================
> --- linux-2.6.16.29.orig/include/asm-i386/pgtable-2level.h 2006-12-29
> 13:56:53.000000000 +0800
> +++ linux-2.6.16.29/include/asm-i386/pgtable-2level.h 2006-12-29
> 13:57:19.612186872 +0800
> @@ -46,21 +46,21 @@
> }
>
> /*
> - * Bits 0, 6 and 7 are taken, split up the 29 bits of offset
> + * Bits 0, 5, 6 and 7 are taken, split up the 28 bits of offset
> * into this range:
> */
> -#define PTE_FILE_MAX_BITS 29
> +#define PTE_FILE_MAX_BITS 28
>
> #define pte_to_pgoff(pte) \
> - ((((pte).pte_low >> 1) & 0x1f ) + (((pte).pte_low >> 8) << 5 ))
> + ((((pte).pte_low >> 1) & 0xf ) + (((pte).pte_low >> 8) << 4 ))
>
> #define pgoff_to_pte(off) \
> - ((pte_t) { (((off) & 0x1f) << 1) + (((off) >> 5) << 8) + _PAGE_FILE
> })
> + ((pte_t) { (((off) & 0xf) << 1) + (((off) >> 4) << 8) + _PAGE_FILE })
>
> /* Encode and de-code a swap entry */
> -#define __swp_type(x) (((x).val >> 1) & 0x1f)
> +#define __swp_type(x) (((x).val >> 1) & 0xf)
> #define __swp_offset(x) ((x).val >> 8)
> -#define __swp_entry(type, offset) ((swp_entry_t) { ((type) << 1) |
> ((offset) << 8) })
> +#define __swp_entry(type, offset) ((swp_entry_t) { ((type & 0xf) <<
> 1) | ((offset) << 8) | _PAGE_SWAPPED })
> #define __pte_to_swp_entry(pte) ((swp_entry_t) {
> (pte).pte_low })
> #define __swp_entry_to_pte(x) ((pte_t) { (x).val })
>
> Index: linux-2.6.16.29/include/asm-i386/pgtable.h
> ===================================================================
> --- linux-2.6.16.29.orig/include/asm-i386/pgtable.h 2006-12-29
> 13:56:53.000000000 +0800
> +++ linux-2.6.16.29/include/asm-i386/pgtable.h 2006-12-29
> 13:57:19.846151304 +0800
> @@ -121,7 +121,11 @@
> #define _PAGE_UNUSED3 0x800
>
> /* If _PAGE_PRESENT is clear, we use these: */
> -#define _PAGE_FILE 0x040 /* nonlinear file mapping, saved PTE;
> unset:swap */
> +#define _PAGE_UNMAPPED 0x020 /* a special PTE type, hold its page
> reference
> + even it's
> unmapped, see more from
> +
> Documentation/vm_pps.txt. */
> +#define _PAGE_SWAPPED 0x040 /* swapped PTE. */
> +#define _PAGE_FILE 0x060 /* nonlinear file mapping, saved PTE; */
> #define _PAGE_PROTNONE 0x080 /* if the user mapped it with PROT_NONE;
> pte_present gives true */
> #ifdef CONFIG_X86_PAE
> @@ -228,7 +232,9 @@
> /*
> * The following only works if pte_present() is not true.
> */
> -static inline int pte_file(pte_t pte) { return (pte).pte_low &
> _PAGE_FILE; }
> +static inline int pte_unmapped(pte_t pte) { return ((pte).pte_low &
> 0x60) == _PAGE_UNMAPPED; }
> +static inline int pte_swapped(pte_t pte) { return ((pte).pte_low &
> 0x60) == _PAGE_SWAPPED; }
> +static inline int pte_file(pte_t pte) { return ((pte).pte_low &
> 0x60) == _PAGE_FILE; }
>
> static inline pte_t pte_rdprotect(pte_t pte) { (pte).pte_low &=
> ~_PAGE_USER; return pte; }
> static inline pte_t pte_exprotect(pte_t pte) { (pte).pte_low &=
> ~_PAGE_USER; return pte; }
> Index: linux-2.6.16.29/include/linux/mm.h
> ===================================================================
> --- linux-2.6.16.29.orig/include/linux/mm.h 2006-12-29
> 13:56:53.000000000 +0800
> +++ linux-2.6.16.29/include/linux/mm.h 2006-12-29 13:57:19.098265000 +0800
> @@ -166,6 +166,8 @@
> #define VM_NONLINEAR 0x00800000 /* Is non-linear (remap_file_pages)
> */
> #define VM_MAPPED_COPY 0x01000000 /* T if mapped copy of data (nommu
> mmap) */
> #define VM_INSERTPAGE 0x02000000 /* The vma has had
> "vm_insert_page()" done on it */
> +#define VM_PURE_PRIVATE 0x04000000 /* Is the vma is only
> belonging to a mm,
> +
> see more from Documentation/vm_pps.txt */
>
> #ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
> #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
> @@ -1056,5 +1058,25 @@
> extern int randomize_va_space;
> #endif
>
> +/* vmscan.c::delay flush TLB */
> +struct delay_tlb_task_t
> +{
> + struct mm_struct* mm;
> + cpumask_t cpu_mask;
> + struct vm_area_struct* vma[32];
> + unsigned long start[32];
> + unsigned long end[32];
> +};
> +extern struct delay_tlb_task_t delay_tlb_tasks[32];
> +
> +// The prototype of the function is fit with the "func" of "int
> +// smp_call_function (void (*func) (void *info), void *info, int retry, int
> +// wait);" of include/linux/smp.h of 2.6.16.29. Call it with NULL.
> +void timer_flush_tlb_tasks(void* data /* = NULL */);
> +
> +void enter_pps(struct mm_struct* mm, struct vm_area_struct* vma);
> +void leave_pps(struct vm_area_struct* vma, int migrate_flag);
> +
> +#define MAX_SERIES_LENGTH 8
> #endif /* __KERNEL__ */
> #endif /* _LINUX_MM_H */
> Index: linux-2.6.16.29/include/linux/swapops.h
> ===================================================================
> --- linux-2.6.16.29.orig/include/linux/swapops.h 2006-12-29
> 13:56:53.000000000 +0800
> +++ linux-2.6.16.29/include/linux/swapops.h 2006-12-29
> 13:57:19.000000000 +0800
> @@ -50,7 +50,7 @@
> {
> swp_entry_t arch_entry;
>
> - BUG_ON(pte_file(pte));
> + BUG_ON(!pte_swapped(pte));
> arch_entry = __pte_to_swp_entry(pte);
> return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
> }
> @@ -64,6 +64,6 @@
> swp_entry_t arch_entry;
>
> arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
> - BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));
> + BUG_ON(!pte_swapped(__swp_entry_to_pte(arch_entry)));
> return __swp_entry_to_pte(arch_entry);
> }
> Index: linux-2.6.16.29/kernel/fork.c
> ===================================================================
> --- linux-2.6.16.29.orig/kernel/fork.c 2006-12-29 13:56:52.000000000 +0800
> +++ linux-2.6.16.29/kernel/fork.c 2006-12-29 13:57:20.000000000 +0800
> @@ -229,6 +229,7 @@
> tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
> if (!tmp)
> goto fail_nomem;
> + leave_pps(mpnt, 1);
> *tmp = *mpnt;
> pol = mpol_copy(vma_policy(mpnt));
> retval = PTR_ERR(pol);
> Index: linux-2.6.16.29/kernel/timer.c
> ===================================================================
> --- linux-2.6.16.29.orig/kernel/timer.c 2006-12-29
> 13:56:52.000000000 +0800
> +++ linux-2.6.16.29/kernel/timer.c 2006-12-29 13:57:20.000000000 +0800
> @@ -842,6 +842,8 @@
> rcu_check_callbacks(cpu, user_tick);
> scheduler_tick();
> run_posix_cpu_timers(p);
> +
> + timer_flush_tlb_tasks(NULL);
> }
>
> /*
> Index: linux-2.6.16.29/mm/fremap.c
> ===================================================================
> --- linux-2.6.16.29.orig/mm/fremap.c 2006-12-29 13:56:51.000000000 +0800
> +++ linux-2.6.16.29/mm/fremap.c 2006-12-29 13:57:21.000000000 +0800
> @@ -37,7 +37,7 @@
> page_cache_release(page);
> }
> } else {
> - if (!pte_file(pte))
> + if (pte_swapped(pte))
> free_swap_and_cache(pte_to_swp_entry(pte));
> pte_clear(mm, addr, ptep);
> }
> Index: linux-2.6.16.29/mm/memory.c
> ===================================================================
> --- linux-2.6.16.29.orig/mm/memory.c 2006-12-29 13:56:52.000000000 +0800
> +++ linux-2.6.16.29/mm/memory.c 2006-12-29 13:57:51.000000000 +0800
> @@ -436,7 +436,7 @@
>
> /* pte contains position in swap or file, so copy. */
> if (unlikely(!pte_present(pte))) {
> - if (!pte_file(pte)) {
> + if (pte_swapped(pte)) {
> swap_duplicate(pte_to_swp_entry(pte));
> /* make sure dst_mm is on swapoff's mmlist. */
> if (unlikely(list_empty(&dst_mm->mmlist))) {
> @@ -658,6 +658,8 @@
> addr) != page->index)
> set_pte_at(mm, addr, pte,
> pgoff_to_pte(page->index));
> + // if (vma->vm_flags & VM_PURE_PRIVATE && page !=
> ZERO_PAGE(addr))
> + // lru_cache_add_active(page);
> if (PageAnon(page))
> anon_rss--;
> else {
> @@ -677,7 +679,16 @@
> */
> if (unlikely(details))
> continue;
> - if (!pte_file(ptent))
> + if (pte_unmapped(ptent)) {
> + struct page *page;
> + page = pfn_to_page(pte_pfn(ptent));
> + pte_clear_full(mm, addr, pte, tlb->fullmm);
> + // lru_cache_add_active(page);
> + tlb_remove_page(tlb, page);
> + anon_rss--;
> + continue;
> + }
> + if (pte_swapped(ptent))
> free_swap_and_cache(pte_to_swp_entry(ptent));
> pte_clear_full(mm, addr, pte, tlb->fullmm);
> } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
> @@ -1508,7 +1519,8 @@
> ptep_establish(vma, address, page_table, entry);
> update_mmu_cache(vma, address, entry);
> lazy_mmu_prot_update(entry);
> - lru_cache_add_active(new_page);
> + if (!(vma->vm_flags & VM_PURE_PRIVATE))
> + lru_cache_add_active(new_page);
> page_add_new_anon_rmap(new_page, vma, address);
>
> /* Free the old page.. */
> @@ -1864,6 +1876,84 @@
> }
>
> /*
> + * New read ahead code, mainly for VM_PURE_PRIVATE only.
> + */
> +static void pps_swapin_readahead(swp_entry_t entry, unsigned long
> addr,struct vm_area_struct *vma, pte_t* pte, pmd_t* pmd)
> +{
> + struct page* page;
> + pte_t *prev, *next;
> + swp_entry_t temp;
> + spinlock_t* ptl = pte_lockptr(vma->vm_mm, pmd);
> + int swapType = swp_type(entry);
> + int swapOffset = swp_offset(entry);
> + int readahead = 1, abs;
> +
> + if (!(vma->vm_flags & VM_PURE_PRIVATE)) {
> + swapin_readahead(entry, addr, vma);
> + return;
> + }
> +
> + page = read_swap_cache_async(entry, vma, addr);
> + if (!page)
> + return;
> + page_cache_release(page);
> +
> + // read ahead the whole series, first forward then backward.
> + while (readahead < MAX_SERIES_LENGTH) {
> + next = pte++;
> + if (next - (pte_t*) pmd >= PTRS_PER_PTE)
> + break;
> + spin_lock(ptl);
> + if (!(!pte_present(*next) && pte_swapped(*next))) {
> + spin_unlock(ptl);
> + break;
> + }
> + temp = pte_to_swp_entry(*next);
> + spin_unlock(ptl);
> + if (swp_type(temp) != swapType)
> + break;
> + abs = swp_offset(temp) - swapOffset;
> + abs = abs < 0 ? -abs : abs;
> + swapOffset = swp_offset(temp);
> + if (abs > 8)
> + // the two swap entries are too far, give up!
> + break;
> + page = read_swap_cache_async(temp, vma, addr);
> + if (!page)
> + return;
> + page_cache_release(page);
> + readahead++;
> + }
> +
> + swapOffset = swp_offset(entry);
> + while (readahead < MAX_SERIES_LENGTH) {
> + prev = pte--;
> + if (prev - (pte_t*) pmd < 0)
> + break;
> + spin_lock(ptl);
> + if (!(!pte_present(*prev) && pte_swapped(*prev))) {
> + spin_unlock(ptl);
> + break;
> + }
> + temp = pte_to_swp_entry(*prev);
> + spin_unlock(ptl);
> + if (swp_type(temp) != swapType)
> + break;
> + abs = swp_offset(temp) - swapOffset;
> + abs = abs < 0 ? -abs : abs;
> + swapOffset = swp_offset(temp);
> + if (abs > 8)
> + // the two swap entries are too far, give up!
> + break;
> + page = read_swap_cache_async(temp, vma, addr);
> + if (!page)
> + return;
> + page_cache_release(page);
> + readahead++;
> + }
> +}
> +
> +/*
> * We enter with non-exclusive mmap_sem (to exclude vma changes,
> * but allow concurrent faults), and pte mapped but not yet locked.
> * We return with mmap_sem still held, but pte unmapped and unlocked.
> @@ -1885,7 +1975,7 @@
> again:
> page = lookup_swap_cache(entry);
> if (!page) {
> - swapin_readahead(entry, address, vma);
> + pps_swapin_readahead(entry, address, vma, page_table, pmd);
> page = read_swap_cache_async(entry, vma, address);
> if (!page) {
> /*
> @@ -1904,10 +1994,15 @@
> grab_swap_token();
> }
>
> - mark_page_accessed(page);
> + if (!(vma->vm_flags & VM_PURE_PRIVATE))
> + mark_page_accessed(page);
> lock_page(page);
> if (!PageSwapCache(page)) {
> /* Page migration has occured */
> + if (vma->vm_flags & VM_PURE_PRIVATE) {
> + lru_cache_add_active(page);
> + mark_page_accessed(page);
> + }
> unlock_page(page);
> page_cache_release(page);
> goto again;
> @@ -1922,6 +2017,10 @@
>
> if (unlikely(!PageUptodate(page))) {
> ret = VM_FAULT_SIGBUS;
> + if (vma->vm_flags & VM_PURE_PRIVATE) {
> + lru_cache_add_active(page);
> + mark_page_accessed(page);
> + }
> goto out_nomap;
> }
>
> @@ -1993,8 +2092,9 @@
> page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
> if (!pte_none(*page_table))
> goto release;
> + if (!(vma->vm_flags & VM_PURE_PRIVATE))
> + lru_cache_add_active(page);
> inc_mm_counter(mm, anon_rss);
> - lru_cache_add_active(page);
> page_add_new_anon_rmap(page, vma, address);
> } else {
> /* Map the ZERO_PAGE - vm_page_prot is readonly */
> @@ -2209,6 +2309,20 @@
>
> old_entry = entry = *pte;
> if (!pte_present(entry)) {
> + if (pte_unmapped(entry)) {
> + BUG_ON(!(vma->vm_flags & VM_PURE_PRIVATE));
> + struct page* page = pte_page(entry);
> + pte_t temp_pte = mk_pte(page, vma->vm_page_prot);
> + pte = pte_offset_map_lock(mm, pmd, address, &ptl);
> + if (unlikely(pte_same(*pte, entry))) {
> + page_add_new_anon_rmap(page, vma, address);
> + set_pte_at(mm, address, pte, temp_pte);
> + update_mmu_cache(vma, address, temp_pte);
> + lazy_mmu_prot_update(temp_pte);
> + }
> + pte_unmap_unlock(pte, ptl);
> + return VM_FAULT_MINOR;
> + }
> if (pte_none(entry)) {
> if (!vma->vm_ops || !vma->vm_ops->nopage)
> return do_anonymous_page(mm, vma, address,
> @@ -2445,3 +2559,112 @@
> }
>
> #endif /* __HAVE_ARCH_GATE_AREA */
> +
> +static void migrate_back_pte_range(struct mm_struct* mm, pmd_t *pmd, struct
> + vm_area_struct *vma, unsigned long addr, unsigned long end)
> +{
> + struct page* page;
> + pte_t entry;
> + pte_t* pte;
> + spinlock_t* ptl;
> +
> + pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
> + do {
> + if (!pte_present(*pte) && pte_unmapped(*pte)) {
> + page = pte_page(*pte);
> + entry = mk_pte(page, vma->vm_page_prot);
> + entry = maybe_mkwrite(pte_mkdirty(entry), vma);
> + set_pte_at(mm, addr, pte, entry);
> + BUG_ON(page == ZERO_PAGE(addr));
> + page_add_new_anon_rmap(page, vma, addr);
> + }
> + if (pte_present(*pte)) {
> + page = pte_page(*pte);
> + if (page == ZERO_PAGE(addr))
> + continue;
> + lru_cache_add_active(page);
> + }
> + } while (pte++, addr += PAGE_SIZE, addr != end);
> + pte_unmap_unlock(pte - 1, ptl);
> + lru_add_drain();
> +}
> +
> +static void migrate_back_pmd_range(struct mm_struct* mm, pud_t *pud, struct
> + vm_area_struct *vma, unsigned long addr, unsigned long end)
> +{
> + pmd_t *pmd;
> + unsigned long next;
> +
> + pmd = pmd_offset(pud, addr);
> + do {
> + next = pmd_addr_end(addr, end);
> + if (pmd_none_or_clear_bad(pmd))
> + continue;
> + migrate_back_pte_range(mm, pmd, vma, addr, next);
> + } while (pmd++, addr = next, addr != end);
> +}
> +
> +static void migrate_back_pud_range(struct mm_struct* mm, pgd_t *pgd, struct
> + vm_area_struct *vma, unsigned long addr, unsigned long end)
> +{
> + pud_t *pud;
> + unsigned long next;
> +
> + pud = pud_offset(pgd, addr);
> + do {
> + next = pud_addr_end(addr, end);
> + if (pud_none_or_clear_bad(pud))
> + continue;
> + migrate_back_pmd_range(mm, pud, vma, addr, next);
> + } while (pud++, addr = next, addr != end);
> +}
> +
> +// migrate all pages of pure private vma back to Linux legacy memory
> management.
> +static void migrate_back_legacy_linux(struct mm_struct* mm, struct
> vm_area_struct* vma)
> +{
> + pgd_t* pgd;
> + unsigned long next;
> + unsigned long addr = vma->vm_start;
> + unsigned long end = vma->vm_end;
> +
> + pgd = pgd_offset(mm, addr);
> + do {
> + next = pgd_addr_end(addr, end);
> + if (pgd_none_or_clear_bad(pgd))
> + continue;
> + migrate_back_pud_range(mm, pgd, vma, addr, next);
> + } while (pgd++, addr = next, addr != end);
> +}
> +
> +LIST_HEAD(pps_head);
> +LIST_HEAD(pps_head_buddy);
> +
> +DEFINE_SPINLOCK(pps_lock);
> +
> +void enter_pps(struct mm_struct* mm, struct vm_area_struct* vma)
> +{
> + int condition = VM_READ | VM_WRITE | VM_EXEC | \
> + VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC | \
> + VM_GROWSDOWN | VM_GROWSUP | \
> + VM_LOCKED | VM_SEQ_READ | VM_RAND_READ | VM_DONTCOPY |
> VM_ACCOUNT;
> + if (!(vma->vm_flags & ~condition) && vma->vm_file == NULL) {
> + vma->vm_flags |= VM_PURE_PRIVATE;
> + if (list_empty(&mm->mmlist)) {
> + spin_lock(&mmlist_lock);
> + if (list_empty(&mm->mmlist))
> + list_add(&mm->mmlist, &init_mm.mmlist);
> + spin_unlock(&mmlist_lock);
> + }
> + }
> +}
> +
> +void leave_pps(struct vm_area_struct* vma, int migrate_flag)
> +{
> + struct mm_struct* mm = vma->vm_mm;
> +
> + if (vma->vm_flags & VM_PURE_PRIVATE) {
> + vma->vm_flags &= ~VM_PURE_PRIVATE;
> + if (migrate_flag)
> + migrate_back_legacy_linux(mm, vma);
> + }
> +}
> Index: linux-2.6.16.29/mm/mmap.c
> ===================================================================
> --- linux-2.6.16.29.orig/mm/mmap.c 2006-12-29 13:56:51.000000000 +0800
> +++ linux-2.6.16.29/mm/mmap.c 2006-12-29 13:57:20.000000000 +0800
> @@ -206,6 +206,7 @@
> if (vma->vm_file)
> fput(vma->vm_file);
> mpol_free(vma_policy(vma));
> + leave_pps(vma, 0);
> kmem_cache_free(vm_area_cachep, vma);
> return next;
> }
> @@ -593,6 +594,7 @@
> fput(file);
> mm->map_count--;
> mpol_free(vma_policy(next));
> + leave_pps(next, 0);
> kmem_cache_free(vm_area_cachep, next);
> /*
> * In mprotect's case 6 (see comments on vma_merge),
> @@ -1091,6 +1093,8 @@
> if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
> vma->vm_flags &= ~VM_ACCOUNT;
>
> + enter_pps(mm, vma);
> +
> /* Can addr have changed??
> *
> * Answer: Yes, several device drivers can do it in their
> @@ -1113,6 +1117,7 @@
> fput(file);
> }
> mpol_free(vma_policy(vma));
> + leave_pps(vma, 0);
> kmem_cache_free(vm_area_cachep, vma);
> }
> out:
> @@ -1140,6 +1145,7 @@
> unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
> charged = 0;
> free_vma:
> + leave_pps(vma, 0);
> kmem_cache_free(vm_area_cachep, vma);
> unacct_error:
> if (charged)
> @@ -1717,6 +1723,10 @@
>
> /* most fields are the same, copy all, and then fixup */
> *new = *vma;
> + if (new->vm_flags & VM_PURE_PRIVATE) {
> + new->vm_flags &= ~VM_PURE_PRIVATE;
> + enter_pps(mm, new);
> + }
>
> if (new_below)
> new->vm_end = addr;
> @@ -1917,6 +1927,7 @@
> vma->vm_pgoff = pgoff;
> vma->vm_flags = flags;
> vma->vm_page_prot = protection_map[flags & 0x0f];
> + enter_pps(mm, vma);
> vma_link(mm, vma, prev, rb_link, rb_parent);
> out:
> mm->total_vm += len >> PAGE_SHIFT;
> @@ -2040,6 +2051,10 @@
> get_file(new_vma->vm_file);
> if (new_vma->vm_ops && new_vma->vm_ops->open)
> new_vma->vm_ops->open(new_vma);
> + if (new_vma->vm_flags & VM_PURE_PRIVATE) {
> + new_vma->vm_flags &= ~VM_PURE_PRIVATE;
> + enter_pps(mm, new_vma);
> + }
> vma_link(mm, new_vma, prev, rb_link, rb_parent);
> }
> }
> Index: linux-2.6.16.29/mm/rmap.c
> ===================================================================
> --- linux-2.6.16.29.orig/mm/rmap.c 2006-12-29 13:56:51.000000000 +0800
> +++ linux-2.6.16.29/mm/rmap.c 2006-12-29 13:57:21.000000000 +0800
> @@ -633,7 +633,7 @@
> spin_unlock(&mmlist_lock);
> }
> set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
> - BUG_ON(pte_file(*pte));
> + BUG_ON(!pte_swapped(*pte));
> dec_mm_counter(mm, anon_rss);
> } else
> dec_mm_counter(mm, file_rss);
> Index: linux-2.6.16.29/mm/swap_state.c
> ===================================================================
> --- linux-2.6.16.29.orig/mm/swap_state.c 2006-12-29
> 13:56:51.000000000 +0800
> +++ linux-2.6.16.29/mm/swap_state.c 2006-12-29 13:57:20.000000000 +0800
> @@ -354,7 +354,8 @@
> /*
> * Initiate read into locked page and return.
> */
> - lru_cache_add_active(new_page);
> + if (vma == NULL || !(vma->vm_flags &
> VM_PURE_PRIVATE))
> + lru_cache_add_active(new_page);
> swap_readpage(NULL, new_page);
> return new_page;
> }
> Index: linux-2.6.16.29/mm/swapfile.c
> ===================================================================
> --- linux-2.6.16.29.orig/mm/swapfile.c 2006-12-29 13:56:52.000000000 +0800
> +++ linux-2.6.16.29/mm/swapfile.c 2006-12-29 13:57:21.000000000 +0800
> @@ -7,6 +7,7 @@
>
> #include <linux/config.h>
> #include <linux/mm.h>
> +#include <linux/mm_inline.h>
> #include <linux/hugetlb.h>
> #include <linux/mman.h>
> #include <linux/slab.h>
> @@ -417,6 +418,163 @@
> }
> }
>
> +static int pps_test_swap_type(struct mm_struct* mm, pmd_t* pmd, pte_t*
> pte, int
> + type, struct page** ret_page)
> +{
> + spinlock_t* ptl = pte_lockptr(mm, pmd);
> + swp_entry_t entry;
> + struct page* page;
> +
> + spin_lock(ptl);
> + if (!pte_present(*pte) && pte_swapped(*pte)) {
> + entry = pte_to_swp_entry(*pte);
> + if (swp_type(entry) == type) {
> + *ret_page = NULL;
> + spin_unlock(ptl);
> + return 1;
> + }
> + } else {
> + page = pfn_to_page(pte_pfn(*pte));
> + if (PageSwapCache(page)) {
> + entry.val = page_private(page);
> + if (swp_type(entry) == type) {
> + page_cache_get(page);
> + *ret_page = page;
> + spin_unlock(ptl);
> + return 1;
> + }
> + }
> + }
> + spin_unlock(ptl);
> + return 0;
> +}
> +
> +static int pps_swapoff_scan_ptes(struct mm_struct* mm, struct
> vm_area_struct*
> + vma, pmd_t* pmd, unsigned long addr, unsigned long end, int
> type)
> +{
> + pte_t *pte;
> + struct page* page;
> +
> + pte = pte_offset_map(pmd, addr);
> + do {
> + while (pps_test_swap_type(mm, pmd, pte, type, &page)) {
> + if (page == NULL) {
> + switch (__handle_mm_fault(mm, vma, addr, 0))
> {
> + case VM_FAULT_SIGBUS:
> + case VM_FAULT_OOM:
> + return -ENOMEM;
> + case VM_FAULT_MINOR:
> + case VM_FAULT_MAJOR:
> + break;
> + default:
> + BUG();
> + }
> + } else {
> + wait_on_page_locked(page);
> + wait_on_page_writeback(page);
> + lock_page(page);
> + if (!PageSwapCache(page)) {
> + unlock_page(page);
> + page_cache_release(page);
> + break;
> + }
> + wait_on_page_writeback(page);
> + delete_from_swap_cache(page);
> + unlock_page(page);
> + page_cache_release(page);
> + break;
> + }
> + }
> + } while (pte++, addr += PAGE_SIZE, addr != end);
> + return 0;
> +}
> +
> +static int pps_swapoff_pmd_range(struct mm_struct* mm, struct
> vm_area_struct*
> + vma, pud_t* pud, unsigned long addr, unsigned long end, int
> type)
> +{
> + unsigned long next;
> + int ret;
> + pmd_t* pmd = pmd_offset(pud, addr);
> + do {
> + next = pmd_addr_end(addr, end);
> + if (pmd_none_or_clear_bad(pmd))
> + continue;
> + ret = pps_swapoff_scan_ptes(mm, vma, pmd, addr, next, type);
> + if (ret == -ENOMEM)
> + return ret;
> + } while (pmd++, addr = next, addr != end);
> + return 0;
> +}
> +
> +static int pps_swapoff_pud_range(struct mm_struct* mm, struct
> vm_area_struct*
> + vma, pgd_t* pgd, unsigned long addr, unsigned long end, int
> type)
> +{
> + unsigned long next;
> + int ret;
> + pud_t* pud = pud_offset(pgd, addr);
> + do {
> + next = pud_addr_end(addr, end);
> + if (pud_none_or_clear_bad(pud))
> + continue;
> + ret = pps_swapoff_pmd_range(mm, vma, pud, addr, next, type);
> + if (ret == -ENOMEM)
> + return ret;
> + } while (pud++, addr = next, addr != end);
> + return 0;
> +}
> +
> +static int pps_swapoff_pgd_range(struct mm_struct* mm, struct
> vm_area_struct*
> + vma, int type)
> +{
> + unsigned long next;
> + unsigned long addr = vma->vm_start;
> + unsigned long end = vma->vm_end;
> + int ret;
> + pgd_t* pgd = pgd_offset(mm, addr);
> + do {
> + next = pgd_addr_end(addr, end);
> + if (pgd_none_or_clear_bad(pgd))
> + continue;
> + ret = pps_swapoff_pud_range(mm, vma, pgd, addr, next, type);
> + if (ret == -ENOMEM)
> + return ret;
> + } while (pgd++, addr = next, addr != end);
> + return 0;
> +}
> +
> +static int pps_swapoff(int type)
> +{
> + struct mm_struct* mm;
> + struct vm_area_struct* vma;
> + struct list_head *pos, *lhtemp;
> + int ret = 0;
> +
> + spin_lock(&mmlist_lock);
> + list_for_each_safe(pos, lhtemp, &init_mm.mmlist) {
> + mm = list_entry(pos, struct mm_struct, mmlist);
> + if (atomic_inc_return(&mm->mm_users) == 1) {
> + atomic_dec(&mm->mm_users);
> + continue;
> + }
> + spin_unlock(&mmlist_lock);
> + down_read(&mm->mmap_sem);
> + for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
> + if (!(vma->vm_flags & VM_PURE_PRIVATE))
> + continue;
> + if (vma->vm_flags & VM_LOCKED)
> + continue;
> + ret = pps_swapoff_pgd_range(mm, vma, type);
> + if (ret == -ENOMEM)
> + break;
> + }
> + up_read(&mm->mmap_sem);
> + mmput(mm);
> + spin_lock(&mmlist_lock);
> + }
> + spin_unlock(&mmlist_lock);
> + return ret;
> +}
> +
> /*
> * No need to decide whether this PTE shares the swap entry with others,
> * just let do_wp_page work it out if a write is requested later - to
> @@ -619,6 +777,12 @@
> int reset_overflow = 0;
> int shmem;
>
> + // Let's first read all pps pages back! Note, it's one-to-one
> mapping.
> + retval = pps_swapoff(type);
> + if (retval == -ENOMEM) // something was wrong.
> + return -ENOMEM;
> + // Now, the remain pages are shared pages, go ahead!
> +
> /*
> * When searching mms for an entry, a good strategy is to
> * start at the first mm we freed the previous entry from
> @@ -848,16 +1012,20 @@
> */
> static void drain_mmlist(void)
> {
> - struct list_head *p, *next;
> + // struct list_head *p, *next;
> unsigned int i;
>
> for (i = 0; i < nr_swapfiles; i++)
> if (swap_info[i].inuse_pages)
> return;
> + /*
> + * Now, init_mm.mmlist list not only is used by SwapDevice but also
> is used
> + * by PPS.
> spin_lock(&mmlist_lock);
> list_for_each_safe(p, next, &init_mm.mmlist)
> list_del_init(p);
> spin_unlock(&mmlist_lock);
> + */
> }
>
> /*
> Index: linux-2.6.16.29/mm/vmscan.c
> ===================================================================
> --- linux-2.6.16.29.orig/mm/vmscan.c 2006-12-29 13:56:51.000000000 +0800
> +++ linux-2.6.16.29/mm/vmscan.c 2006-12-29 13:58:30.000000000 +0800
> @@ -1514,6 +1514,398 @@
> return ret;
> }
>
> +struct series_t {
> + pte_t orig_ptes[MAX_SERIES_LENGTH];
> + pte_t* ptes[MAX_SERIES_LENGTH];
> + struct page* pages[MAX_SERIES_LENGTH];
> + int series_length;
> + int series_stage;
> +} series;
> +
> +static int get_series_stage(pte_t* pte, int index)
> +{
> + series.orig_ptes[index] = *pte;
> + series.ptes[index] = pte;
> + if (pte_present(series.orig_ptes[index])) {
> + struct page* page =
> pfn_to_page(pte_pfn(series.orig_ptes[index]));
> + series.pages[index] = page;
> + if (page == ZERO_PAGE(addr)) // reserved page is exclusive
> from us.
> + return 7;
> + if (pte_young(series.orig_ptes[index])) {
> + return 1;
> + } else
> + return 2;
> + } else if (pte_unmapped(series.orig_ptes[index])) {
> + struct page* page =
> pfn_to_page(pte_pfn(series.orig_ptes[index]));
> + series.pages[index] = page;
> + if (!PageSwapCache(page))
> + return 3;
> + else {
> + if (PageWriteback(page) || PageDirty(page))
> + return 4;
> + else
> + return 5;
> + }
> + } else // pte_swapped -- SwappedPTE
> + return 6;
> +}
> +
> +static void find_series(pte_t** start, unsigned long* addr, unsigned long
> end)
> +{
> + int i;
> + int series_stage = get_series_stage((*start)++, 0);
> + *addr += PAGE_SIZE;
> +
> + for (i = 1; i < MAX_SERIES_LENGTH && *addr < end; i++, (*start)++,
> *addr += PAGE_SIZE) {
> + if (series_stage != get_series_stage(*start, i))
> + break;
> + }
> + series.series_stage = series_stage;
> + series.series_length = i;
> +}
> +
> +struct delay_tlb_task_t delay_tlb_tasks[32] = { [0 ... 31] = {0} };
> +
> +void timer_flush_tlb_tasks(void* data)
> +{
> + // To x86, if we found there were some flushing tasks, we should do
> it all together, that is, flush it once.
> + int i;
> +#ifdef CONFIG_X86
> + int flag = 0;
> +#endif
> + for (i = 0; i < 32; i++) {
> + if (delay_tlb_tasks[i].mm != NULL &&
> + cpu_isset(smp_processor_id(),
> delay_tlb_tasks[i].mm->cpu_vm_mask) &&
> + cpu_isset(smp_processor_id(),
> delay_tlb_tasks[i].cpu_mask)) {
> +#ifdef CONFIG_X86
> + flag = 1;
> +#elif
> + // smp::local_flush_tlb_range(delay_tlb_tasks[i]);
> +#endif
> + cpu_clear(smp_processor_id(),
> delay_tlb_tasks[i].cpu_mask);
> + }
> + }
> +#ifdef CONFIG_X86
> + if (flag)
> + local_flush_tlb();
> +#endif
> +}
> +
> +static struct delay_tlb_task_t* delay_task = NULL;
> +static int vma_index = 0;
> +
> +static struct delay_tlb_task_t* search_free_tlb_tasks_slot(void)
> +{
> + struct delay_tlb_task_t* ret = NULL;
> + int i;
> +again:
> + for (i = 0; i < 32; i++) {
> + if (delay_tlb_tasks[i].mm != NULL) {
> + if (cpus_empty(delay_tlb_tasks[i].cpu_mask)) {
> + mmput(delay_tlb_tasks[i].mm);
> + delay_tlb_tasks[i].mm = NULL;
> + ret = &delay_tlb_tasks[i];
> + }
> + } else
> + ret = &delay_tlb_tasks[i];
> + }
> + if (!ret) { // Force flush TLBs.
> + on_each_cpu(timer_flush_tlb_tasks, NULL, 0, 1);
> + goto again;
> + }
> + return ret;
> +}
> +
> +static void init_delay_task(struct mm_struct* mm)
> +{
> + cpus_clear(delay_task->cpu_mask);
> + vma_index = 0;
> + delay_task->mm = mm;
> +}
> +
> +/*
> + * We will be working on the mm, so let's force to flush it if necessary.
> + */
> +static void start_tlb_tasks(struct mm_struct* mm)
> +{
> + int i, flag = 0;
> +again:
> + for (i = 0; i < 32; i++) {
> + if (delay_tlb_tasks[i].mm == mm) {
> + if (cpus_empty(delay_tlb_tasks[i].cpu_mask)) {
> + mmput(delay_tlb_tasks[i].mm);
> + delay_tlb_tasks[i].mm = NULL;
> + } else
> + flag = 1;
> + }
> + }
> + if (flag) { // Force flush TLBs.
> + on_each_cpu(timer_flush_tlb_tasks, NULL, 0, 1);
> + goto again;
> + }
> + BUG_ON(delay_task != NULL);
> + delay_task = search_free_tlb_tasks_slot();
> + init_delay_task(mm);
> +}
> +
> +static void end_tlb_tasks(void)
> +{
> + if (!cpus_empty(delay_task->cpu_mask)) {
> + atomic_inc(&delay_task->mm->mm_users);
> + delay_task->cpu_mask = delay_task->mm->cpu_vm_mask;
> + } else
> + delay_task->mm = NULL;
> + delay_task = NULL;
> +}
> +
> +static void fill_in_tlb_tasks(struct vm_area_struct* vma, unsigned long
> addr,
> + unsigned long end)
> +{
> + struct mm_struct* mm;
> +fill_it:
> + if (vma_index != 32) {
> + delay_task->vma[vma_index] = vma;
> + delay_task->start[vma_index] = addr;
> + delay_task->end[vma_index] = end;
> + vma_index++;
> + return;
> + }
> + mm = delay_task->mm;
> + end_tlb_tasks();
> +
> + delay_task = search_free_tlb_tasks_slot();
> + init_delay_task(mm);
> + goto fill_it;
> +}
> +
> +static void shrink_pvma_scan_ptes(struct scan_control* sc,
> + struct mm_struct* mm, struct vm_area_struct* vma, pmd_t* pmd,
> + unsigned long addr, unsigned long end)
> +{
> + int i;
> + spinlock_t* ptl = pte_lockptr(mm, pmd);
> + pte_t* pte = pte_offset_map(pmd, addr);
> + int anon_rss = 0;
> + struct pagevec freed_pvec;
> + int may_enter_fs = (sc->gfp_mask & (__GFP_FS | __GFP_IO));
> + struct address_space* mapping = &swapper_space;
> +
> + pagevec_init(&freed_pvec, 1);
> + do {
> + memset(&series, 0, sizeof(struct series_t));
> + find_series(&pte, &addr, end);
> + switch (series.series_stage) {
> + case 1: // PTE -- untouched PTE.
> + for (i = 0; i < series.series_length; i++) {
> + struct page* page = series.pages[i];
> + lock_page(page);
> + spin_lock(ptl);
> + if
> (unlikely(pte_same(*series.ptes[i], series.orig_ptes[i]))) {
> + if
> (pte_dirty(*series.ptes[i]))
> + set_page_dirty(page);
> + set_pte_at(mm, addr + i *
> PAGE_SIZE, series.ptes[i],
> +
> pte_mkold(pte_mkclean(*series.ptes[i])));
> + }
> + spin_unlock(ptl);
> + unlock_page(page);
> + }
> + fill_in_tlb_tasks(vma, addr, addr +
> (PAGE_SIZE * series.series_length));
> + break;
> + case 2: // untouched PTE -- UnmappedPTE.
> + /*
> + * Note in stage 1, we've flushed TLB in
> fill_in_tlb_tasks, so
> + * if it's still clear here, we can shift it
> to Unmapped type.
> + *
> + * If some architecture doesn't support
> atomic cmpxchg
> + * instruction or can't atomically set the
> access bit after
> + * they touch a pte at first, combine stage
> 1 with stage 2, and
> + * send IPI immediately in fill_in_tlb_tasks.
> + */
> + spin_lock(ptl);
> + for (i = 0; i < series.series_length; i++) {
> + if
> (unlikely(pte_same(*series.ptes[i], series.orig_ptes[i]))) {
> + pte_t pte_unmapped =
> series.orig_ptes[i];
> + pte_unmapped.pte_low &=
> ~_PAGE_PRESENT;
> + pte_unmapped.pte_low |=
> _PAGE_UNMAPPED;
> + if
> (cmpxchg(&series.ptes[i]->pte_low,
> +
> series.orig_ptes[i].pte_low,
> +
> pte_unmapped.pte_low) !=
> +
> series.orig_ptes[i].pte_low)
> + continue;
> + page_remove_rmap(series.pages[i]);
> + anon_rss--;
> + }
> + }
> + spin_unlock(ptl);
> + break;
> + case 3: // Attach SwapPage to PrivatePage.
> + /*
> + * A better arithmetic should be applied to
> Linux SwapDevice to
> + * allocate fake continual SwapPages which
> are close to each
> + * other, the offset between two close
> SwapPages is less than 8.
> + */
> + if (sc->may_swap) {
> + for (i = 0; i <
> series.series_length; i++) {
> + lock_page(series.pages[i]);
> + if
> (!PageSwapCache(series.pages[i])) {
> + if
> (!add_to_swap(series.pages[i], GFP_ATOMIC)) {
> +
> unlock_page(series.pages[i]);
> + break;
> + }
> + }
> + unlock_page(series.pages[i]);
> + }
> + }
> + break;
> + case 4: // SwapPage isn't consistent with
> PrivatePage.
> + /*
> + * A mini version pageout().
> + *
> + * Current swap space can't commit multiple
> pages together:(
> + */
> + if (sc->may_writepage && may_enter_fs) {
> + for (i = 0; i <
> series.series_length; i++) {
> + struct page* page =
> series.pages[i];
> + int res;
> +
> + if
> (!may_write_to_queue(mapping->backing_dev_info))
> + break;
> + lock_page(page);
> + if (!PageDirty(page) ||
> PageWriteback(page)) {
> + unlock_page(page);
> + continue;
> + }
> + clear_page_dirty_for_io(page);
> + struct writeback_control wbc
> = {
> + .sync_mode =
> WB_SYNC_NONE,
> + .nr_to_write =
> SWAP_CLUSTER_MAX,
> + .nonblocking = 1,
> + .for_reclaim = 1,
> + };
> + page_cache_get(page);
> + SetPageReclaim(page);
> + res = swap_writepage(page,
> &wbc);
> + if (res < 0) {
> + handle_write_error(mapping,
> page, res);
> + ClearPageReclaim(page);
> + page_cache_release(page);
> + break;
> + }
> + if (!PageWriteback(page))
> + ClearPageReclaim(page);
> + page_cache_release(page);
> + }
> + }
> + break;
> + case 5: // UnmappedPTE -- SwappedPTE, reclaim
> PrivatePage.
> + for (i = 0; i < series.series_length; i++) {
> + struct page* page = series.pages[i];
> + lock_page(page);
> + spin_lock(ptl);
> + if
> (unlikely(pte_same(*series.ptes[i], series.orig_ptes[i]))) {
> + spin_unlock(ptl);
> + unlock_page(page);
> + continue;
> + }
> + swp_entry_t entry = { .val =
> page_private(page) };
> + swap_duplicate(entry);
> + pte_t pte_swp =
> swp_entry_to_pte(entry);
> + set_pte_at(mm, addr + i * PAGE_SIZE,
> series.ptes[i], pte_swp);
> + spin_unlock(ptl);
> + if (PageSwapCache(page) &&
> !PageWriteback(page))
> + delete_from_swap_cache(page);
> + unlock_page(page);
> +
> + if (!pagevec_add(&freed_pvec, page))
> +
> __pagevec_release_nonlru(&freed_pvec);
> + sc->nr_reclaimed++;
> + }
> + break;
> + case 6:
> + // NULL operation!
> + break;
> + }
> + } while (addr < end);
> + add_mm_counter(mm, anon_rss, anon_rss);
> + if (pagevec_count(&freed_pvec))
> + __pagevec_release_nonlru(&freed_pvec);
> +}
> +
> +static void shrink_pvma_pmd_range(struct scan_control* sc, struct
> mm_struct* mm,
> + struct vm_area_struct* vma, pud_t* pud,
> + unsigned long addr, unsigned long end)
> +{
> + unsigned long next;
> + pmd_t* pmd = pmd_offset(pud, addr);
> + do {
> + next = pmd_addr_end(addr, end);
> + if (pmd_none_or_clear_bad(pmd))
> + continue;
> + shrink_pvma_scan_ptes(sc, mm, vma, pmd, addr, next);
> + } while (pmd++, addr = next, addr != end);
> +}
> +
> +static void shrink_pvma_pud_range(struct scan_control* sc, struct
> mm_struct* mm,
> + struct vm_area_struct* vma, pgd_t* pgd,
> + unsigned long addr, unsigned long end)
> +{
> + unsigned long next;
> + pud_t* pud = pud_offset(pgd, addr);
> + do {
> + next = pud_addr_end(addr, end);
> + if (pud_none_or_clear_bad(pud))
> + continue;
> + shrink_pvma_pmd_range(sc, mm, vma, pud, addr, next);
> + } while (pud++, addr = next, addr != end);
> +}
> +
> +static void shrink_pvma_pgd_range(struct scan_control* sc, struct
> mm_struct* mm,
> + struct vm_area_struct* vma)
> +{
> + unsigned long next;
> + unsigned long addr = vma->vm_start;
> + unsigned long end = vma->vm_end;
> + pgd_t* pgd = pgd_offset(mm, addr);
> + do {
> + next = pgd_addr_end(addr, end);
> + if (pgd_none_or_clear_bad(pgd))
> + continue;
> + shrink_pvma_pud_range(sc, mm, vma, pgd, addr, next);
> + } while (pgd++, addr = next, addr != end);
> +}
> +
> +static void shrink_private_vma(struct scan_control* sc)
> +{
> + struct mm_struct* mm;
> + struct vm_area_struct* vma;
> + struct list_head *pos, *lhtemp;
> +
> + spin_lock(&mmlist_lock);
> + list_for_each_safe(pos, lhtemp, &init_mm.mmlist) {
> + mm = list_entry(pos, struct mm_struct, mmlist);
> + if (atomic_inc_return(&mm->mm_users) == 1) {
> + atomic_dec(&mm->mm_users);
> + continue;
> + }
> + spin_unlock(&mmlist_lock);
> + start_tlb_tasks(mm);
> + if (down_read_trylock(&mm->mmap_sem)) {
> + for (vma = mm->mmap; vma != NULL; vma =
> vma->vm_next) {
> + if (!(vma->vm_flags & VM_PURE_PRIVATE))
> + continue;
> + if (vma->vm_flags & VM_LOCKED)
> + continue;
> + shrink_pvma_pgd_range(sc, mm, vma);
> + }
> + up_read(&mm->mmap_sem);
> + }
> + end_tlb_tasks();
> + mmput(mm);
> + spin_lock(&mmlist_lock);
> + }
> + spin_unlock(&mmlist_lock);
> +}
> +
> /*
> * For kswapd, balance_pgdat() will work across all this node's zones until
> * they are all at pages_high.
> @@ -1557,6 +1949,7 @@
> sc.may_swap = 1;
> sc.nr_mapped = read_page_state(nr_mapped);
>
> + shrink_private_vma(&sc);
> inc_page_state(pageoutrun);
>
> for (i = 0; i < pgdat->nr_zones; i++) {

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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