Re: [PATCH 05/10] memcg: add dirty page accounting infrastructure

[Minchan Kim]

On Sun, Oct 03, 2010 at 11:58:00PM -0700, Greg Thelen wrote:
> Add memcg routines to track dirty, writeback, and unstable_NFS pages.
> These routines are not yet used by the kernel to count such pages.
> A later change adds kernel calls to these new routines.
> 
> Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
> Signed-off-by: Andrea Righi <arighi@xxxxxxxxxxx>
> ---
>  include/linux/memcontrol.h |    3 +
>  mm/memcontrol.c            |   89 ++++++++++++++++++++++++++++++++++++++++----
>  2 files changed, 84 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 7c7bec4..6303da1 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -28,6 +28,9 @@ struct mm_struct;
>  /* Stats that can be updated by kernel. */
>  enum mem_cgroup_write_page_stat_item {
>  	MEMCG_NR_FILE_MAPPED, /* # of pages charged as file rss */
> +	MEMCG_NR_FILE_DIRTY, /* # of dirty pages in page cache */
> +	MEMCG_NR_FILE_WRITEBACK, /* # of pages under writeback */
> +	MEMCG_NR_FILE_UNSTABLE_NFS, /* # of NFS unstable pages */
>  };
>  
>  extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 267d774..f40839f 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -85,10 +85,13 @@ enum mem_cgroup_stat_index {
>  	 */
>  	MEM_CGROUP_STAT_CACHE, 	   /* # of pages charged as cache */
>  	MEM_CGROUP_STAT_RSS,	   /* # of pages charged as anon rss */
> -	MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
>  	MEM_CGROUP_STAT_PGPGIN_COUNT,	/* # of pages paged in */
>  	MEM_CGROUP_STAT_PGPGOUT_COUNT,	/* # of pages paged out */
>  	MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
> +	MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
> +	MEM_CGROUP_STAT_FILE_DIRTY,	/* # of dirty pages in page cache */
> +	MEM_CGROUP_STAT_FILE_WRITEBACK,		/* # of pages under writeback */
> +	MEM_CGROUP_STAT_FILE_UNSTABLE_NFS,	/* # of NFS unstable pages */
>  	MEM_CGROUP_STAT_DATA, /* end of data requires synchronization */
>  	/* incremented at every  pagein/pageout */
>  	MEM_CGROUP_EVENTS = MEM_CGROUP_STAT_DATA,
> @@ -1626,6 +1629,48 @@ void mem_cgroup_update_page_stat(struct page *page,
>  			ClearPageCgroupFileMapped(pc);
>  		idx = MEM_CGROUP_STAT_FILE_MAPPED;
>  		break;
> +
> +	case MEMCG_NR_FILE_DIRTY:
> +		/* Use Test{Set,Clear} to only un/charge the memcg once. */
> +		if (val > 0) {
> +			if (TestSetPageCgroupFileDirty(pc))
> +				/* already set */

Nitpick. 
The comment doesn't give any useful information.
It looks like redundant. 

> +				val = 0;
> +		} else {
> +			if (!TestClearPageCgroupFileDirty(pc))
> +				/* already cleared */

Ditto

> +				val = 0;
> +		}
> +		idx = MEM_CGROUP_STAT_FILE_DIRTY;
> +		break;
> +
> +	case MEMCG_NR_FILE_WRITEBACK:
> +		/*
> +		 * This counter is adjusted while holding the mapping's
> +		 * tree_lock.  Therefore there is no race between settings and
> +		 * clearing of this flag.
> +		 */
> +		if (val > 0)
> +			SetPageCgroupFileWriteback(pc);
> +		else
> +			ClearPageCgroupFileWriteback(pc);
> +		idx = MEM_CGROUP_STAT_FILE_WRITEBACK;
> +		break;
> +
> +	case MEMCG_NR_FILE_UNSTABLE_NFS:
> +		/* Use Test{Set,Clear} to only un/charge the memcg once. */
> +		if (val > 0) {
> +			if (TestSetPageCgroupFileUnstableNFS(pc))
> +				/* already set */

Ditto 

> +				val = 0;
> +		} else {
> +			if (!TestClearPageCgroupFileUnstableNFS(pc))
> +				/* already cleared */

Ditto 

> +				val = 0;
> +		}
> +		idx = MEM_CGROUP_STAT_FILE_UNSTABLE_NFS;
> +		break;
> +
>  	default:
>  		BUG();
>  	}
> @@ -2133,6 +2178,16 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
>  	memcg_check_events(mem, pc->page);
>  }
>  
> +static void mem_cgroup_move_account_page_stat(struct mem_cgroup *from,
> +					      struct mem_cgroup *to,
> +					      enum mem_cgroup_stat_index idx)
> +{
> +	preempt_disable();
> +	__this_cpu_dec(from->stat->count[idx]);
> +	__this_cpu_inc(to->stat->count[idx]);
> +	preempt_enable();
> +}
> +
>  /**
>   * __mem_cgroup_move_account - move account of the page
>   * @pc:	page_cgroup of the page.
> @@ -2159,13 +2214,18 @@ static void __mem_cgroup_move_account(struct page_cgroup *pc,
>  	VM_BUG_ON(!PageCgroupUsed(pc));
>  	VM_BUG_ON(pc->mem_cgroup != from);
>  
> -	if (PageCgroupFileMapped(pc)) {
> -		/* Update mapped_file data for mem_cgroup */
> -		preempt_disable();
> -		__this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
> -		__this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
> -		preempt_enable();
> -	}
> +	if (PageCgroupFileMapped(pc))
> +		mem_cgroup_move_account_page_stat(from, to,
> +					MEM_CGROUP_STAT_FILE_MAPPED);
> +	if (PageCgroupFileDirty(pc))
> +		mem_cgroup_move_account_page_stat(from, to,
> +					MEM_CGROUP_STAT_FILE_DIRTY);
> +	if (PageCgroupFileWriteback(pc))
> +		mem_cgroup_move_account_page_stat(from, to,
> +					MEM_CGROUP_STAT_FILE_WRITEBACK);
> +	if (PageCgroupFileUnstableNFS(pc))
> +		mem_cgroup_move_account_page_stat(from, to,
> +					MEM_CGROUP_STAT_FILE_UNSTABLE_NFS);
>  	mem_cgroup_charge_statistics(from, pc, false);
>  	if (uncharge)
>  		/* This is not "cancel", but cancel_charge does all we need. */
> @@ -3545,6 +3605,9 @@ enum {
>  	MCS_PGPGIN,
>  	MCS_PGPGOUT,
>  	MCS_SWAP,
> +	MCS_FILE_DIRTY,
> +	MCS_WRITEBACK,
> +	MCS_UNSTABLE_NFS,
>  	MCS_INACTIVE_ANON,
>  	MCS_ACTIVE_ANON,
>  	MCS_INACTIVE_FILE,
> @@ -3567,6 +3630,9 @@ struct {
>  	{"pgpgin", "total_pgpgin"},
>  	{"pgpgout", "total_pgpgout"},
>  	{"swap", "total_swap"},
> +	{"dirty", "total_dirty"},
> +	{"writeback", "total_writeback"},
> +	{"nfs", "total_nfs"},
>  	{"inactive_anon", "total_inactive_anon"},
>  	{"active_anon", "total_active_anon"},
>  	{"inactive_file", "total_inactive_file"},
> @@ -3596,6 +3662,13 @@ mem_cgroup_get_local_stat(struct mem_cgroup *mem, struct mcs_total_stat *s)
>  		s->stat[MCS_SWAP] += val * PAGE_SIZE;
>  	}
>  
> +	val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_DIRTY);
> +	s->stat[MCS_FILE_DIRTY] += val * PAGE_SIZE;
> +	val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_WRITEBACK);
> +	s->stat[MCS_WRITEBACK] += val * PAGE_SIZE;
> +	val = mem_cgroup_read_stat(mem, MEM_CGROUP_STAT_FILE_UNSTABLE_NFS);
> +	s->stat[MCS_UNSTABLE_NFS] += val * PAGE_SIZE;
> +
>  	/* per zone stat */
>  	val = mem_cgroup_get_local_zonestat(mem, LRU_INACTIVE_ANON);
>  	s->stat[MCS_INACTIVE_ANON] += val * PAGE_SIZE;
> -- 
> 1.7.1
> 
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-- 
Kind regards,
Minchan Kim
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