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

From: yunfeng zhang
Date: Fri Dec 29 2006 - 01:48:16 EST

Next message: Linus Torvalds: "Re: [PATCH] mm: fix page_mkclean_one"
Previous message: Dave Jones: "compile fix for via-pmu-backlight"
In reply to: Pavel Machek: "Re: [PATCH 2.6.16.29 1/1] memory: enhance Linux swap subsystem"
Next in thread: Pavel Machek: "Re: [PATCH 2.6.16.29 1/1] memory: enhance Linux swap subsystem"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

I've re-published my work on quilt, sorry.

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++) {
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Linus Torvalds: "Re: [PATCH] mm: fix page_mkclean_one"
Previous message: Dave Jones: "compile fix for via-pmu-backlight"
In reply to: Pavel Machek: "Re: [PATCH 2.6.16.29 1/1] memory: enhance Linux swap subsystem"
Next in thread: Pavel Machek: "Re: [PATCH 2.6.16.29 1/1] memory: enhance Linux swap subsystem"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]