[PATCH v3 05/11] memcg: add dirty page accounting infrastructure

Greg Thelen
2010-10-19T00:42:55Z

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@google.com>
Signed-off-by: Andrea Righi <arighi@develer.com>
---

Changelog since v1:
- Renamed "nfs"/"total_nfs" to "nfs_unstable"/"total_nfs_unstable" in per cgroup
memory.stat to match /proc/meminfo.
- Rename (for clarity):
- mem_cgroup_write_page_stat_item -> mem_cgroup_page_stat_item
- mem_cgroup_read_page_stat_item -> mem_cgroup_nr_pages_item
- Remove redundant comments.
- Made mem_cgroup_move_account_page_stat() inline.

include/linux/memcontrol.h | 3 ++
mm/memcontrol.c | 86 +++++++++++++++++++++++++++++++++++++++----
2 files changed, 81 insertions(+), 8 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 067115c..ef2eec7 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_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 697f7b8..3ac2693 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,
@@ -1642,6 +1645,44 @@ 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))
+ val = 0;
+ } else {
+ if (!TestClearPageCgroupFileDirty(pc))
+ 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))
+ val = 0;
+ } else {
+ if (!TestClearPageCgroupFileUnstableNFS(pc))
+ val = 0;
+ }
+ idx = MEM_CGROUP_STAT_FILE_UNSTABLE_NFS;
+ break;
+
default:
BUG();
}
@@ -2146,6 +2187,17 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
memcg_check_events(mem, pc->page);
}

+static inline
+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.
@@ -2172,13 +2224,18 @@ 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. */
@@ -3557,6 +3614,9 @@ enum {
MCS_PGPGIN,
MCS_PGPGOUT,
MCS_SWAP,
+ MCS_FILE_DIRTY,
+ MCS_WRITEBACK,
+ MCS_UNSTABLE_NFS,
MCS_INACTIVE_ANON,
MCS_ACTIVE_ANON,
MCS_INACTIVE_FILE,
@@ -3579,6 +3639,9 @@ struct {
{"pgpgin", "total_pgpgin"},
{"pgpgout", "total_pgpgout"},
{"swap", "total_swap"},
+ {"dirty", "total_dirty"},
+ {"writeback", "total_writeback"},
+ {"nfs_unstable", "total_nfs_unstable"},
{"inactive_anon", "total_inactive_anon"},
{"active_anon", "total_active_anon"},
{"inactive_file", "total_inactive_file"},
@@ -3608,6 +3671,13 @@ 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