Re: [PATCH 2/2] memcg: dirty pages instrumentation

From: Vivek Goyal
Date: Mon Feb 22 2010 - 11:54:43 EST

On Sun, Feb 21, 2010 at 04:18:45PM +0100, Andrea Righi wrote:
> Apply the cgroup dirty pages accounting and limiting infrastructure to
> the opportune kernel functions.
>
> Signed-off-by: Andrea Righi <arighi@xxxxxxxxxxx>
> ---
> fs/fuse/file.c | 3 ++
> fs/nfs/write.c | 3 ++
> fs/nilfs2/segment.c | 8 ++++-
> mm/filemap.c | 1 +
> mm/page-writeback.c | 69 ++++++++++++++++++++++++++++++++++++--------------
> mm/truncate.c | 1 +
> 6 files changed, 63 insertions(+), 22 deletions(-)
>
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index a9f5e13..357632a 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -11,6 +11,7 @@
> #include <linux/pagemap.h>
> #include <linux/slab.h>
> #include <linux/kernel.h>
> +#include <linux/memcontrol.h>
> #include <linux/sched.h>
> #include <linux/module.h>
>
> @@ -1129,6 +1130,7 @@ static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req)
>
> list_del(&req->writepages_entry);
> dec_bdi_stat(bdi, BDI_WRITEBACK);
> + mem_cgroup_charge_dirty(req->pages[0], NR_WRITEBACK_TEMP, -1);
> dec_zone_page_state(req->pages[0], NR_WRITEBACK_TEMP);
> bdi_writeout_inc(bdi);
> wake_up(&fi->page_waitq);
> @@ -1240,6 +1242,7 @@ static int fuse_writepage_locked(struct page *page)
> req->inode = inode;
>
> inc_bdi_stat(mapping->backing_dev_info, BDI_WRITEBACK);
> + mem_cgroup_charge_dirty(tmp_page, NR_WRITEBACK_TEMP, 1);
> inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP);
> end_page_writeback(page);
>
> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> index d63d964..3d9de01 100644
> --- a/fs/nfs/write.c
> +++ b/fs/nfs/write.c
> @@ -439,6 +439,7 @@ nfs_mark_request_commit(struct nfs_page *req)
> req->wb_index,
> NFS_PAGE_TAG_COMMIT);
> spin_unlock(&inode->i_lock);
> + mem_cgroup_charge_dirty(req->wb_page, NR_UNSTABLE_NFS, 1);
> inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
> inc_bdi_stat(req->wb_page->mapping->backing_dev_info, BDI_RECLAIMABLE);
> __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
> @@ -450,6 +451,7 @@ nfs_clear_request_commit(struct nfs_page *req)
> struct page *page = req->wb_page;
>
> if (test_and_clear_bit(PG_CLEAN, &(req)->wb_flags)) {
> + mem_cgroup_charge_dirty(page, NR_UNSTABLE_NFS, -1);
> dec_zone_page_state(page, NR_UNSTABLE_NFS);
> dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
> return 1;
> @@ -1320,6 +1322,7 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how)
> req = nfs_list_entry(head->next);
> nfs_list_remove_request(req);
> nfs_mark_request_commit(req);
> + mem_cgroup_charge_dirty(req->wb_page, NR_UNSTABLE_NFS, -1);
> dec_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
> dec_bdi_stat(req->wb_page->mapping->backing_dev_info,
> BDI_RECLAIMABLE);
> diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
> index 105b508..b9ffac5 100644
> --- a/fs/nilfs2/segment.c
> +++ b/fs/nilfs2/segment.c
> @@ -1660,8 +1660,10 @@ nilfs_copy_replace_page_buffers(struct page *page, struct list_head *out)
> } while (bh = bh->b_this_page, bh2 = bh2->b_this_page, bh != head);
> kunmap_atomic(kaddr, KM_USER0);
>
> - if (!TestSetPageWriteback(clone_page))
> + if (!TestSetPageWriteback(clone_page)) {
> + mem_cgroup_charge_dirty(clone_page, NR_WRITEBACK, 1);
> inc_zone_page_state(clone_page, NR_WRITEBACK);
> + }
> unlock_page(clone_page);
>
> return 0;
> @@ -1788,8 +1790,10 @@ static void __nilfs_end_page_io(struct page *page, int err)
> }
>
> if (buffer_nilfs_allocated(page_buffers(page))) {
> - if (TestClearPageWriteback(page))
> + if (TestClearPageWriteback(page)) {
> + mem_cgroup_charge_dirty(clone_page, NR_WRITEBACK, -1);
> dec_zone_page_state(page, NR_WRITEBACK);
> + }
> } else
> end_page_writeback(page);
> }
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 698ea80..c19d809 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -135,6 +135,7 @@ void __remove_from_page_cache(struct page *page)
> * having removed the page entirely.
> */
> if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
> + mem_cgroup_charge_dirty(page, NR_FILE_DIRTY, -1);
> dec_zone_page_state(page, NR_FILE_DIRTY);
> dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
> }
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 0b19943..c9ff1cd 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -137,10 +137,11 @@ static struct prop_descriptor vm_dirties;
> */
> static int calc_period_shift(void)
> {
> - unsigned long dirty_total;
> + unsigned long dirty_total, dirty_bytes;
>
> - if (vm_dirty_bytes)
> - dirty_total = vm_dirty_bytes / PAGE_SIZE;
> + dirty_bytes = mem_cgroup_dirty_bytes();
> + if (dirty_bytes)
> + dirty_total = dirty_bytes / PAGE_SIZE;
> else
> dirty_total = (vm_dirty_ratio * determine_dirtyable_memory()) /
> 100;
> @@ -406,14 +407,20 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
> */
> unsigned long determine_dirtyable_memory(void)
> {
> - unsigned long x;
> -
> - x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
> -
> + unsigned long memcg_memory, memory;
> +
> + memory = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
> + memcg_memory = mem_cgroup_page_state(MEMCG_NR_FREE_PAGES);
> + if (memcg_memory > 0) {

it could be just

if (memcg_memory) {
}

> + memcg_memory +=
> + mem_cgroup_page_state(MEMCG_NR_RECLAIMABLE_PAGES);
> + if (memcg_memory < memory)
> + return memcg_memory;
> + }
> if (!vm_highmem_is_dirtyable)
> - x -= highmem_dirtyable_memory(x);
> + memory -= highmem_dirtyable_memory(memory);
>

If vm_highmem_is_dirtyable=0, In that case, we can still return with
"memcg_memory" which can be more than "memory". IOW, highmem is not
dirtyable system wide but still we can potetially return back saying
for this cgroup we can dirty more pages which can potenailly be acutally
be more that system wide allowed?

Because you have modified dirtyable_memory() and made it per cgroup, I
think it automatically takes care of the cases of per cgroup dirty ratio,
I mentioned in my previous mail. So we will use system wide dirty ratio
to calculate the allowed dirty pages in this cgroup (dirty_ratio *
available_memory()) and if this cgroup wrote too many pages start
writeout?

> - return x + 1; /* Ensure that we never return 0 */
> + return memory + 1; /* Ensure that we never return 0 */
> }
>
> void
> @@ -421,12 +428,13 @@ get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
> unsigned long *pbdi_dirty, struct backing_dev_info *bdi)
> {
> unsigned long background;
> - unsigned long dirty;
> + unsigned long dirty, dirty_bytes;
> unsigned long available_memory = determine_dirtyable_memory();
> struct task_struct *tsk;
>
> - if (vm_dirty_bytes)
> - dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
> + dirty_bytes = mem_cgroup_dirty_bytes();
> + if (dirty_bytes)
> + dirty = DIV_ROUND_UP(dirty_bytes, PAGE_SIZE);
> else {
> int dirty_ratio;
>
> @@ -505,9 +513,17 @@ static void balance_dirty_pages(struct address_space *mapping,
> get_dirty_limits(&background_thresh, &dirty_thresh,
> &bdi_thresh, bdi);
>
> - nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
> + nr_reclaimable = mem_cgroup_page_state(MEMCG_NR_FILE_DIRTY);
> + if (nr_reclaimable == 0) {
> + nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
> global_page_state(NR_UNSTABLE_NFS);
> - nr_writeback = global_page_state(NR_WRITEBACK);
> + nr_writeback = global_page_state(NR_WRITEBACK);
> + } else {
> + nr_reclaimable +=
> + mem_cgroup_page_state(MEMCG_NR_UNSTABLE_NFS);
> + nr_writeback =
> + mem_cgroup_page_state(MEMCG_NR_WRITEBACK);
> + }
>
> bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
> bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK);
> @@ -660,6 +676,8 @@ void throttle_vm_writeout(gfp_t gfp_mask)
> unsigned long dirty_thresh;
>
> for ( ; ; ) {
> + unsigned long dirty;
> +
> get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
>
> /*
> @@ -668,10 +686,15 @@ void throttle_vm_writeout(gfp_t gfp_mask)
> */
> dirty_thresh += dirty_thresh / 10; /* wheeee... */
>
> - if (global_page_state(NR_UNSTABLE_NFS) +
> - global_page_state(NR_WRITEBACK) <= dirty_thresh)
> - break;
> - congestion_wait(BLK_RW_ASYNC, HZ/10);
> + dirty = mem_cgroup_page_state(MEMCG_NR_WRITEBACK);
> + if (dirty < 0)

dirty is unsigned long. Will above condition be ever true?

Are you expecting that NR_WRITEBACK can go negative?

Vivek

> + dirty = global_page_state(NR_UNSTABLE_NFS) +
> + global_page_state(NR_WRITEBACK);
> + else
> + dirty += mem_cgroup_page_state(MEMCG_NR_UNSTABLE_NFS);
> + if (dirty <= dirty_thresh)
> + break;
> + congestion_wait(BLK_RW_ASYNC, HZ/10);
>
> /*
> * The caller might hold locks which can prevent IO completion
> @@ -1078,6 +1101,7 @@ int __set_page_dirty_no_writeback(struct page *page)
> void account_page_dirtied(struct page *page, struct address_space *mapping)
> {
> if (mapping_cap_account_dirty(mapping)) {
> + mem_cgroup_charge_dirty(page, NR_FILE_DIRTY, 1);
> __inc_zone_page_state(page, NR_FILE_DIRTY);
> __inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
> task_dirty_inc(current);
> @@ -1253,6 +1277,7 @@ int clear_page_dirty_for_io(struct page *page)
> * for more comments.
> */
> if (TestClearPageDirty(page)) {
> + mem_cgroup_charge_dirty(page, NR_FILE_DIRTY, -1);
> dec_zone_page_state(page, NR_FILE_DIRTY);
> dec_bdi_stat(mapping->backing_dev_info,
> BDI_RECLAIMABLE);
> @@ -1288,8 +1313,10 @@ int test_clear_page_writeback(struct page *page)
> } else {
> ret = TestClearPageWriteback(page);
> }
> - if (ret)
> + if (ret) {
> + mem_cgroup_charge_dirty(page, NR_WRITEBACK, -1);
> dec_zone_page_state(page, NR_WRITEBACK);
> + }
> return ret;
> }
>
> @@ -1319,8 +1346,10 @@ int test_set_page_writeback(struct page *page)
> } else {
> ret = TestSetPageWriteback(page);
> }
> - if (!ret)
> + if (!ret) {
> + mem_cgroup_charge_dirty(page, NR_WRITEBACK, 1);
> inc_zone_page_state(page, NR_WRITEBACK);
> + }
> return ret;
>
> }
> diff --git a/mm/truncate.c b/mm/truncate.c
> index e87e372..f44e370 100644
> --- a/mm/truncate.c
> +++ b/mm/truncate.c
> @@ -73,6 +73,7 @@ void cancel_dirty_page(struct page *page, unsigned int account_size)
> if (TestClearPageDirty(page)) {
> struct address_space *mapping = page->mapping;
> if (mapping && mapping_cap_account_dirty(mapping)) {
> + mem_cgroup_charge_dirty(page, NR_FILE_DIRTY, -1);
> dec_zone_page_state(page, NR_FILE_DIRTY);
> dec_bdi_stat(mapping->backing_dev_info,
> BDI_RECLAIMABLE);
> --
> 1.6.3.3
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