On Wed, 9 Nov 2011 16:05:36 -0800 Ying Han <yinghan@xxxxxxxxxx> wrote: > On Wed, Nov 9, 2011 at 2:44 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > On Fri, 4 Nov 2011 17:15:21 +0800 > > Wanlong Gao <gaowanlong@xxxxxxxxxxxxxx> wrote: > > > > > Pagefault count has added to memcg stats since commit 456f998e, > > > but forgot to doc it. > > > > > > Signed-off-by: Wanlong Gao <gaowanlong@xxxxxxxxxxxxxx> > > > --- > > > Documentation/cgroups/memory.txt | 7 +++++++ > > > 1 files changed, 7 insertions(+), 0 deletions(-) > > > > > > diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt > > > index cc0ebc5..081f4f44 100644 > > > --- a/Documentation/cgroups/memory.txt > > > +++ b/Documentation/cgroups/memory.txt > > > @@ -389,6 +389,13 @@ mapped_file - # of bytes of mapped file (includes tmpfs/shmem) > > > pgpgin - # of pages paged in (equivalent to # of charging events). > > > pgpgout - # of pages paged out (equivalent to # of uncharging events). > > > swap - # of bytes of swap usage > > > + > > > +pgfault - # of page-faults > > > +pgmajfault - # of major page-faults > > > + These two are different from "pgpgin"/"pgpgout" stat which > > > + count number of pages charged/discharged to the cgroup and > > > + have no meaning of reading/writing page to disk. > > > + > > > inactive_anon - # of bytes of anonymous memory and swap cache memory on > > > > OK, but the documentation was already rather poor. > > > > For a start, what do pgpgin and pgpgout actually count? How about > > > > pgpgin: the number of pages read from disk as a result of pagefault > > activity within this memcg (swapin and mapped-file pagein). Does not > > include other causes of disk I/O such as read(). > > > > pgpgout: the number of pages written to disk as a result of swap and > > mapped-file activity within this memcg. Does not include other causes > > of disk I/O such as write(). > > > > (I'm really not sure if this is correct!) > > Andrew, > I am afraid those two stats in memcg world have different perspective > than the ones in vmstat. Wow. Ouch. > They are only incremented/decremented during > charge/uncharge, which is regardless of having IO involved. The > existing documentation isn't that clear i agree. How about: > > pgpgin - # of 4k page charging events to the memory cgroup > pgpgout - # of 4k page uncharging events to the memory cgroup Did we tell readers what a "charging event" is? What do these numbers represent if the machine is using 16k pages? And what do pgfault/pgmajfault mean within memcg? I now fear to ask - given the pgpgin/pgpgout situation, these are probably related to my shampoo viscosity or something :( -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
