Re: [PATCH -mmotm 2/5] memcg: dirty memory documentation

[Greg Thelen <gthelen@google.com>]

On Mon, Mar 15, 2010 at 11:41 PM, Daisuke Nishimura
<nishimura@mxp.nes.nec.co.jp> wrote:
> On Mon, 15 Mar 2010 00:26:39 +0100, Andrea Righi <arighi@develer.com> wrote:
>> Document cgroup dirty memory interfaces and statistics.
>>
>> Signed-off-by: Andrea Righi <arighi@develer.com>
>> ---
>>  Documentation/cgroups/memory.txt |   36 ++++++++++++++++++++++++++++++++++++
>>  1 files changed, 36 insertions(+), 0 deletions(-)
>>
>> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
>> index 49f86f3..38ca499 100644
>> --- a/Documentation/cgroups/memory.txt
>> +++ b/Documentation/cgroups/memory.txt
>> @@ -310,6 +310,11 @@ cache            - # of bytes of page cache memory.
>>  rss          - # of bytes of anonymous and swap cache memory.
>>  pgpgin               - # of pages paged in (equivalent to # of charging events).
>>  pgpgout              - # of pages paged out (equivalent to # of uncharging events).
>> +filedirty    - # of pages that are waiting to get written back to the disk.
>> +writeback    - # of pages that are actively being written back to the disk.
>> +writeback_tmp        - # of pages used by FUSE for temporary writeback buffers.
>> +nfs          - # of NFS pages sent to the server, but not yet committed to
>> +               the actual storage.

Should these new memory.stat counters (filedirty, etc) report byte
counts rather than page counts?  I am thinking that byte counters
would make reporting more obvious depending on how heterogeneous page
sizes are used. Byte counters would also agree with /proc/meminfo.
Within the kernel we could still maintain page counts.  The only
change would be to the reporting routine, mem_cgroup_get_local_stat(),
which would scale the page counts by PAGE_SIZE as it does for for
cache,rss,etc.

--
Greg

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