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Date: Sat, 16 Jun 2012 15:34:24 +0900 From: Kamezawa Hiroyuki <kamezawa.hiroyu@...fujitsu.com> To: Greg Thelen <gthelen@...gle.com> CC: Sha Zhengju <handai.szj@...il.com>, linux-mm@...ck.org, cgroups@...r.kernel.org, yinghan@...gle.com, akpm@...ux-foundation.org, linux-kernel@...r.kernel.org, Sha Zhengju <handai.szj@...bao.com> Subject: Re: [PATCH 2/2] memcg: add per cgroup dirty pages accounting (2012/06/16 0:32), Greg Thelen wrote: > On Fri, Jun 15 2012, Sha Zhengju wrote: > >> This patch adds memcg routines to count dirty pages. I notice that >> the list has talked about per-cgroup dirty page limiting >> (http://lwn.net/Articles/455341/) before, but it did not get merged. > > Good timing, I was just about to make another effort to get some of > these patches upstream. Like you, I was going to start with some basic > counters. > > Your approach is similar to what I have in mind. While it is good to > use the existing PageDirty flag, rather than introducing a new > page_cgroup flag, there are locking complications (see below) to handle > races between moving pages between memcg and the pages being {un}marked > dirty. > >> I've no idea how is this going now, but maybe we can add per cgroup >> dirty pages accounting first. This allows the memory controller to >> maintain an accurate view of the amount of its memory that is dirty >> and can provide some infomation while group's direct reclaim is working. >> >> After commit 89c06bd5 (memcg: use new logic for page stat accounting), >> we do not need per page_cgroup flag anymore and can directly use >> struct page flag. >> >> >> Signed-off-by: Sha Zhengju<handai.szj@...bao.com> >> --- >> include/linux/memcontrol.h | 1 + >> mm/filemap.c | 1 + >> mm/memcontrol.c | 32 +++++++++++++++++++++++++------- >> mm/page-writeback.c | 2 ++ >> mm/truncate.c | 1 + >> 5 files changed, 30 insertions(+), 7 deletions(-) >> >> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h >> index a337c2e..8154ade 100644 >> --- a/include/linux/memcontrol.h >> +++ b/include/linux/memcontrol.h >> @@ -39,6 +39,7 @@ enum mem_cgroup_stat_index { >> MEM_CGROUP_STAT_FILE_MAPPED, /* # of pages charged as file rss */ >> MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */ >> MEM_CGROUP_STAT_DATA, /* end of data requires synchronization */ >> + MEM_CGROUP_STAT_FILE_DIRTY, /* # of dirty pages in page cache */ >> MEM_CGROUP_STAT_NSTATS, >> }; >> >> diff --git a/mm/filemap.c b/mm/filemap.c >> index 79c4b2b..5b5c121 100644 >> --- a/mm/filemap.c >> +++ b/mm/filemap.c >> @@ -141,6 +141,7 @@ 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, MEM_CGROUP_STAT_FILE_DIRTY); > > You need to use mem_cgroup_{begin,end}_update_page_stat around critical > sections that: > 1) check PageDirty > 2) update MEM_CGROUP_STAT_FILE_DIRTY counter > > This protects against the page from being moved between memcg while > accounting. Same comment applies to all of your new calls to > mem_cgroup_{dec,inc}_page_stat. For usage pattern, see > page_add_file_rmap. > If you feel some difficulty with mem_cgroup_{begin,end}_update_page_stat(), please let me know...I hope they should work enough.... Thanks, -Kame -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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