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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2011-07-26 16:08:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-07-26 16:49:42 -0700
commit82f9d486e59f588c7d100865c36510644abda356 (patch)
tree266f3dcf4f57538196bddd77a129adfb2752335b /Documentation
parent108b6a78463bb8c7163e4f9779f36ad8bbade334 (diff)
memcg: add memory.vmscan_stat
The commit log of 0ae5e89c60c9 ("memcg: count the soft_limit reclaim in...") says it adds scanning stats to memory.stat file. But it doesn't because we considered we needed to make a concensus for such new APIs. This patch is a trial to add memory.scan_stat. This shows - the number of scanned pages(total, anon, file) - the number of rotated pages(total, anon, file) - the number of freed pages(total, anon, file) - the number of elaplsed time (including sleep/pause time) for both of direct/soft reclaim. The biggest difference with oringinal Ying's one is that this file can be reset by some write, as # echo 0 ...../memory.scan_stat Example of output is here. This is a result after make -j 6 kernel under 300M limit. [kamezawa@bluextal ~]$ cat /cgroup/memory/A/memory.scan_stat [kamezawa@bluextal ~]$ cat /cgroup/memory/A/memory.vmscan_stat scanned_pages_by_limit 9471864 scanned_anon_pages_by_limit 6640629 scanned_file_pages_by_limit 2831235 rotated_pages_by_limit 4243974 rotated_anon_pages_by_limit 3971968 rotated_file_pages_by_limit 272006 freed_pages_by_limit 2318492 freed_anon_pages_by_limit 962052 freed_file_pages_by_limit 1356440 elapsed_ns_by_limit 351386416101 scanned_pages_by_system 0 scanned_anon_pages_by_system 0 scanned_file_pages_by_system 0 rotated_pages_by_system 0 rotated_anon_pages_by_system 0 rotated_file_pages_by_system 0 freed_pages_by_system 0 freed_anon_pages_by_system 0 freed_file_pages_by_system 0 elapsed_ns_by_system 0 scanned_pages_by_limit_under_hierarchy 9471864 scanned_anon_pages_by_limit_under_hierarchy 6640629 scanned_file_pages_by_limit_under_hierarchy 2831235 rotated_pages_by_limit_under_hierarchy 4243974 rotated_anon_pages_by_limit_under_hierarchy 3971968 rotated_file_pages_by_limit_under_hierarchy 272006 freed_pages_by_limit_under_hierarchy 2318492 freed_anon_pages_by_limit_under_hierarchy 962052 freed_file_pages_by_limit_under_hierarchy 1356440 elapsed_ns_by_limit_under_hierarchy 351386416101 scanned_pages_by_system_under_hierarchy 0 scanned_anon_pages_by_system_under_hierarchy 0 scanned_file_pages_by_system_under_hierarchy 0 rotated_pages_by_system_under_hierarchy 0 rotated_anon_pages_by_system_under_hierarchy 0 rotated_file_pages_by_system_under_hierarchy 0 freed_pages_by_system_under_hierarchy 0 freed_anon_pages_by_system_under_hierarchy 0 freed_file_pages_by_system_under_hierarchy 0 elapsed_ns_by_system_under_hierarchy 0 total_xxxx is for hierarchy management. This will be useful for further memcg developments and need to be developped before we do some complicated rework on LRU/softlimit management. This patch adds a new struct memcg_scanrecord into scan_control struct. sc->nr_scanned at el is not designed for exporting information. For example, nr_scanned is reset frequentrly and incremented +2 at scanning mapped pages. To avoid complexity, I added a new param in scan_control which is for exporting scanning score. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ying Han <yinghan@google.com> Cc: Andrew Bresticker <abrestic@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/cgroups/memory.txt85
1 files changed, 84 insertions, 1 deletions
diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 06eb6d957c8..6f3c598971f 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -380,7 +380,7 @@ will be charged as a new owner of it.
5.2 stat file
-memory.stat file includes following statistics
+5.2.1 memory.stat file includes following statistics
# per-memory cgroup local status
cache - # of bytes of page cache memory.
@@ -438,6 +438,89 @@ Note:
file_mapped is accounted only when the memory cgroup is owner of page
cache.)
+5.2.2 memory.vmscan_stat
+
+memory.vmscan_stat includes statistics information for memory scanning and
+freeing, reclaiming. The statistics shows memory scanning information since
+memory cgroup creation and can be reset to 0 by writing 0 as
+
+ #echo 0 > ../memory.vmscan_stat
+
+This file contains following statistics.
+
+[param]_[file_or_anon]_pages_by_[reason]_[under_heararchy]
+[param]_elapsed_ns_by_[reason]_[under_hierarchy]
+
+For example,
+
+ scanned_file_pages_by_limit indicates the number of scanned
+ file pages at vmscan.
+
+Now, 3 parameters are supported
+
+ scanned - the number of pages scanned by vmscan
+ rotated - the number of pages activated at vmscan
+ freed - the number of pages freed by vmscan
+
+If "rotated" is high against scanned/freed, the memcg seems busy.
+
+Now, 2 reason are supported
+
+ limit - the memory cgroup's limit
+ system - global memory pressure + softlimit
+ (global memory pressure not under softlimit is not handled now)
+
+When under_hierarchy is added in the tail, the number indicates the
+total memcg scan of its children and itself.
+
+elapsed_ns is a elapsed time in nanosecond. This may include sleep time
+and not indicates CPU usage. So, please take this as just showing
+latency.
+
+Here is an example.
+
+# cat /cgroup/memory/A/memory.vmscan_stat
+scanned_pages_by_limit 9471864
+scanned_anon_pages_by_limit 6640629
+scanned_file_pages_by_limit 2831235
+rotated_pages_by_limit 4243974
+rotated_anon_pages_by_limit 3971968
+rotated_file_pages_by_limit 272006
+freed_pages_by_limit 2318492
+freed_anon_pages_by_limit 962052
+freed_file_pages_by_limit 1356440
+elapsed_ns_by_limit 351386416101
+scanned_pages_by_system 0
+scanned_anon_pages_by_system 0
+scanned_file_pages_by_system 0
+rotated_pages_by_system 0
+rotated_anon_pages_by_system 0
+rotated_file_pages_by_system 0
+freed_pages_by_system 0
+freed_anon_pages_by_system 0
+freed_file_pages_by_system 0
+elapsed_ns_by_system 0
+scanned_pages_by_limit_under_hierarchy 9471864
+scanned_anon_pages_by_limit_under_hierarchy 6640629
+scanned_file_pages_by_limit_under_hierarchy 2831235
+rotated_pages_by_limit_under_hierarchy 4243974
+rotated_anon_pages_by_limit_under_hierarchy 3971968
+rotated_file_pages_by_limit_under_hierarchy 272006
+freed_pages_by_limit_under_hierarchy 2318492
+freed_anon_pages_by_limit_under_hierarchy 962052
+freed_file_pages_by_limit_under_hierarchy 1356440
+elapsed_ns_by_limit_under_hierarchy 351386416101
+scanned_pages_by_system_under_hierarchy 0
+scanned_anon_pages_by_system_under_hierarchy 0
+scanned_file_pages_by_system_under_hierarchy 0
+rotated_pages_by_system_under_hierarchy 0
+rotated_anon_pages_by_system_under_hierarchy 0
+rotated_file_pages_by_system_under_hierarchy 0
+freed_pages_by_system_under_hierarchy 0
+freed_anon_pages_by_system_under_hierarchy 0
+freed_file_pages_by_system_under_hierarchy 0
+elapsed_ns_by_system_under_hierarchy 0
+
5.3 swappiness
Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.