...otherwise the we're getting the wrong numbers in usage_in_bytes.
On Mon, Mar 05, 2012 at 09:19:34AM +0900, KAMEZAWA Hiroyuki wrote: [...]
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 228d646..c8abdc5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3812,6 +3812,9 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE); val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);
Is there any particular reason we don't currently account file mapped memory in usage_in_bytes?
To me, MEM_CGROUP_STAT_FILE_MAPPED hunk seems logical even if we don't use it for lowmemory notifications.
Plus, it seems that FILE_MAPPED _is_ accounted for the non-root cgroups, so I guess it's clearly a bug for the root memcg?
CACHE includes all file caches. Why do you think FILE_MAPPED is not included in CACHE ?
There were tons of changes in the memcg lately, but I believe the issue is still there.
For example, looking into this code flow:
-> page_add_file_rmap() (mm/rmap.c) -> mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED) (include/linux/memcontrol.h) -> void mem_cgroup_update_page_stat(page, MEMCG_NR_FILE_MAPPED, 1) (mm/memcontrol.c)
And then:
void mem_cgroup_update_page_stat(struct page *page, enum mem_cgroup_page_stat_item idx, int val) { ... switch (idx) { case MEMCG_NR_FILE_MAPPED: idx = MEM_CGROUP_STAT_FILE_MAPPED; break; default: BUG(); }
this_cpu_add(memcg->stat->count[idx], val); ... }
So, clearly, this function only bothers updating _FILE_MAPPED only, leaving _CACHE alone.
If you're saying that _CACHE meant to include _FILE_MAPPED, then I guess the patch down below would be a proper fix then... Otherwise we need to be consistent on stats reporting, and either fall-back to my original fix (in mem_cgroup_usage()), or think about doing it some other way...
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org ---
The patch is against current -next.
Thanks,
mm/memcontrol.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 884e936..760ecf5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1958,6 +1958,8 @@ void mem_cgroup_update_page_stat(struct page *page,
switch (idx) { case MEMCG_NR_FILE_MAPPED: + idx = MEM_CGROUP_STAT_CACHE; + this_cpu_add(memcg->stat->count[idx], val); idx = MEM_CGROUP_STAT_FILE_MAPPED; break; default:
(2012/04/23 17:28), Anton Vorontsov wrote:
...otherwise the we're getting the wrong numbers in usage_in_bytes.
On Mon, Mar 05, 2012 at 09:19:34AM +0900, KAMEZAWA Hiroyuki wrote: [...]
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 228d646..c8abdc5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3812,6 +3812,9 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE); val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED);
Is there any particular reason we don't currently account file mapped memory in usage_in_bytes?
To me, MEM_CGROUP_STAT_FILE_MAPPED hunk seems logical even if we don't use it for lowmemory notifications.
Plus, it seems that FILE_MAPPED _is_ accounted for the non-root cgroups, so I guess it's clearly a bug for the root memcg?
CACHE includes all file caches. Why do you think FILE_MAPPED is not included in CACHE ?
There were tons of changes in the memcg lately, but I believe the issue is still there.
For example, looking into this code flow:
-> page_add_file_rmap() (mm/rmap.c) -> mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED) (include/linux/memcontrol.h) -> void mem_cgroup_update_page_stat(page, MEMCG_NR_FILE_MAPPED, 1) (mm/memcontrol.c)
And then:
void mem_cgroup_update_page_stat(struct page *page, enum mem_cgroup_page_stat_item idx, int val) { ... switch (idx) { case MEMCG_NR_FILE_MAPPED: idx = MEM_CGROUP_STAT_FILE_MAPPED; break; default: BUG(); }
this_cpu_add(memcg->stat->count[idx], val); ...}
So, clearly, this function only bothers updating _FILE_MAPPED only, leaving _CACHE alone.
If you're saying that _CACHE meant to include _FILE_MAPPED, then I guess the patch down below would be a proper fix then... Otherwise we need to be consistent on stats reporting, and either fall-back to my original fix (in mem_cgroup_usage()), or think about doing it some other way...
NACK. CACHE is updated at charge()/uncharge()...inserting/removing page cache to radix-tree.
Thanks, -Kame
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org
The patch is against current -next.
Thanks,
mm/memcontrol.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 884e936..760ecf5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1958,6 +1958,8 @@ void mem_cgroup_update_page_stat(struct page *page, switch (idx) { case MEMCG_NR_FILE_MAPPED:
idx = MEM_CGROUP_STAT_CACHE;this_cpu_add(memcg->stat->count[idx], val);
On Mon, Apr 23, 2012 at 05:35:12PM +0900, KAMEZAWA Hiroyuki wrote: [...]
For example, looking into this code flow:
-> page_add_file_rmap() (mm/rmap.c) -> mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED) (include/linux/memcontrol.h) -> void mem_cgroup_update_page_stat(page, MEMCG_NR_FILE_MAPPED, 1) (mm/memcontrol.c)
And then:
void mem_cgroup_update_page_stat(struct page *page, enum mem_cgroup_page_stat_item idx, int val) { ... switch (idx) { case MEMCG_NR_FILE_MAPPED: idx = MEM_CGROUP_STAT_FILE_MAPPED; break; default: BUG(); }
this_cpu_add(memcg->stat->count[idx], val); ...}
So, clearly, this function only bothers updating _FILE_MAPPED only, leaving _CACHE alone.
[...]
NACK. CACHE is updated at charge()/uncharge()...inserting/removing page cache to radix-tree.
Interesting; true, we have charge/uncharge in __do_fault()/do_wp_page and friends. So, we seem to update FILE_MAPPED in the rmap via cgroup_dec/inc_page_stat, and CACHE is updated via charge/uncharge. Hm.
The code in memory.c is full of if/else ifs, and I wonder if there's some discrepancy in there, but briefly looking it looks fine. The code looks correct indeed, but I'm getting the wrong stats. :-/
Thanks,
linaro-kernel@lists.linaro.org
-
Anton Vorontsov -
KAMEZAWA Hiroyuki