Re: [PATCH v6 4/9] memcg: add kernel calls for memcg dirty page stats
From: Greg Thelen
Date: Tue Mar 15 2011 - 02:33:10 EST
On Mon, Mar 14, 2011 at 8:10 AM, Minchan Kim <minchan.kim@xxxxxxxxx> wrote:
> On Fri, Mar 11, 2011 at 10:43:26AM -0800, Greg Thelen wrote:
>> Add calls into memcg dirty page accounting. Notify memcg when pages
>> transition between clean, file dirty, writeback, and unstable nfs.
>> This allows the memory controller to maintain an accurate view of
>> the amount of its memory that is dirty.
>>
>> Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
>> Signed-off-by: Andrea Righi <arighi@xxxxxxxxxxx>
>> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>> Reviewed-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
>> ---
>> Changelog since v5:
>> - moved accounting site in test_clear_page_writeback() and
>> test_set_page_writeback().
>>
>> fs/nfs/write.c | 4 ++++
>> mm/filemap.c | 1 +
>> mm/page-writeback.c | 10 ++++++++--
>> mm/truncate.c | 1 +
>> 4 files changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
>> index 42b92d7..7863777 100644
>> --- a/fs/nfs/write.c
>> +++ b/fs/nfs/write.c
>> @@ -451,6 +451,7 @@ nfs_mark_request_commit(struct nfs_page *req)
>> NFS_PAGE_TAG_COMMIT);
>> nfsi->ncommit++;
>> spin_unlock(&inode->i_lock);
>> + mem_cgroup_inc_page_stat(req->wb_page, MEMCG_NR_FILE_UNSTABLE_NFS);
>> 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);
>> @@ -462,6 +463,7 @@ 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_dec_page_stat(page, MEMCG_NR_FILE_UNSTABLE_NFS);
>> dec_zone_page_state(page, NR_UNSTABLE_NFS);
>> dec_bdi_stat(page->mapping->backing_dev_info, BDI_RECLAIMABLE);
>> return 1;
>> @@ -1319,6 +1321,8 @@ 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_dec_page_stat(req->wb_page,
>> + MEMCG_NR_FILE_UNSTABLE_NFS);
>> 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/mm/filemap.c b/mm/filemap.c
>> index a6cfecf..7e751fe 100644
>> --- a/mm/filemap.c
>> +++ b/mm/filemap.c
>> @@ -143,6 +143,7 @@ void __delete_from_page_cache(struct page *page)
>> * having removed the page entirely.
>> */
>> if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
>> + mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_DIRTY);
>> 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 632b464..d8005b0 100644
>> --- a/mm/page-writeback.c
>> +++ b/mm/page-writeback.c
>> @@ -1118,6 +1118,7 @@ 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_inc_page_stat(page, MEMCG_NR_FILE_DIRTY);
>> __inc_zone_page_state(page, NR_FILE_DIRTY);
>> __inc_zone_page_state(page, NR_DIRTIED);
>> __inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
>> @@ -1317,6 +1318,7 @@ int clear_page_dirty_for_io(struct page *page)
>> * for more comments.
>> */
>> if (TestClearPageDirty(page)) {
>> + mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_DIRTY);
>> dec_zone_page_state(page, NR_FILE_DIRTY);
>> dec_bdi_stat(mapping->backing_dev_info,
>> BDI_RECLAIMABLE);
>> @@ -1352,8 +1354,10 @@ int test_clear_page_writeback(struct page *page)
>> } else {
>> ret = TestClearPageWriteback(page);
>> }
>> - if (ret)
>> + if (ret) {
>> + mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_WRITEBACK);
>> dec_zone_page_state(page, NR_WRITEBACK);
>> + }
>> return ret;
>> }
>>
>> @@ -1386,8 +1390,10 @@ int test_set_page_writeback(struct page *page)
>> } else {
>> ret = TestSetPageWriteback(page);
>> }
>> - if (!ret)
>> + if (!ret) {
>> + mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_WRITEBACK);
>> account_page_writeback(page);
>> + }
>> return ret;
>>
>> }
>
> At least in mainline, NR_WRITEBACK handling codes are following as.
>
> 1) increase
>
> * account_page_writeback
>
> 2) decrease
>
> * test_clear_page_writeback
> * __nilfs_end_page_io
>
> I think account_page_writeback name is good to add your account function into that.
> The problem is decreasement. Normall we can handle decreasement in test_clear_page_writeback.
> But I am not sure it's okay in __nilfs_end_page_io.
> I think if __nilfs_end_page_io is right, __nilfs_end_page_io should call
> mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_WRITEBACK).
>
> What do you think about it?
>
>
>
> --
> Kind regards,
> Minchan Kim
>
I would like to not have any special cases that avoid certain memory.
So I think your suggestion is good.
However, nilfs memcg dirty page accounting was skipped in a previous
memcg dirty limit effort due to complexity. See 'clone_page'
reference in:
http://lkml.indiana.edu/hypermail/linux/kernel/1003.0/02997.html
I admit that I don't follow all of the nilfs code path, but it looks
like some of the nilfs pages are allocated but not charged to memcg.
There is code in mem_cgroup_update_page_stat() to gracefully handle
pages not associated with a memcg. So perhaps nilfs clone pages dirty
[un]charge could be attempted. I have not succeeded in testing in
exercising these code paths in nilfs.
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