Re: [PATCH V2] Add the pagefault count into memcg stats

[Ying Han <yinghan@google.com>]

On Mon, Mar 28, 2011 at 4:17 PM, Minchan Kim <minchan.kim@gmail.com> wrote:
> On Mon, Mar 28, 2011 at 12:26 PM, Ying Han <yinghan@google.com> wrote:
>> Two new stats in per-memcg memory.stat which tracks the number of
>> page faults and number of major page faults.
>>
>> "pgfault"
>> "pgmajfault"
>>
>> They 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.
>>
>> It is valuable to track the two stats for both measuring application's
>> performance as well as the efficiency of the kernel page reclaim path.
>> Counting pagefaults per process is useful, but we also need the aggregated
>> value since processes are monitored and controlled in cgroup basis in memcg.
>>
>> Functional test: check the total number of pgfault/pgmajfault of all
>> memcgs and compare with global vmstat value:
>>
>> $ cat /proc/vmstat | grep fault
>> pgfault 1070751
>> pgmajfault 553
>>
>> $ cat /dev/cgroup/memory.stat | grep fault
>> pgfault 1071138
>> pgmajfault 553
>> total_pgfault 1071142
>> total_pgmajfault 553
>>
>> $ cat /dev/cgroup/A/memory.stat | grep fault
>> pgfault 199
>> pgmajfault 0
>> total_pgfault 199
>> total_pgmajfault 0
>>
>> Performance test: run page fault test(pft) wit 16 thread on faulting in 15G
>> anon pages in 16G container. There is no regression noticed on the "flt/cpu/s"
>>
>> Sample output from pft:
>> TAG pft:anon-sys-default:
>>  Gb  Thr CLine   User     System     Wall    flt/cpu/s fault/wsec
>>  15   16   1     0.69s   230.99s    14.62s   16972.539 268876.196
>>
>> +-------------------------------------------------------------------------+
>>    N           Min           Max        Median           Avg        Stddev
>> x  10     16682.962     17344.027     16913.524     16928.812      166.5362
>> +  10      16718.92     17023.453     16907.164     16902.399     88.468851
>> No difference proven at 95.0% confidence
>>
>> Signed-off-by: Ying Han <yinghan@google.com>
>> ---
>>  Documentation/cgroups/memory.txt |    4 +++
>>  fs/ncpfs/mmap.c                  |    2 +
>>  include/linux/memcontrol.h       |   18 ++++++++++++++
>>  mm/filemap.c                     |    1 +
>>  mm/memcontrol.c                  |   47 ++++++++++++++++++++++++++++++++++++++
>>  mm/memory.c                      |    2 +
>>  mm/shmem.c                       |    2 +
>>  7 files changed, 76 insertions(+), 0 deletions(-)
>>
>> diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
>> index b6ed61c..2db6103 100644
>> --- a/Documentation/cgroups/memory.txt
>> +++ b/Documentation/cgroups/memory.txt
>> @@ -385,6 +385,8 @@ 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.
>>  inactive_anon  - # of bytes of anonymous memory and swap cache memory on
>>                LRU list.
>>  active_anon    - # of bytes of anonymous and swap cache memory on active
>> @@ -406,6 +408,8 @@ total_mapped_file   - sum of all children's "cache"
>>  total_pgpgin           - sum of all children's "pgpgin"
>>  total_pgpgout          - sum of all children's "pgpgout"
>>  total_swap             - sum of all children's "swap"
>> +total_pgfault          - sum of all children's "pgfault"
>> +total_pgmajfault       - sum of all children's "pgmajfault"
>>  total_inactive_anon    - sum of all children's "inactive_anon"
>>  total_active_anon      - sum of all children's "active_anon"
>>  total_inactive_file    - sum of all children's "inactive_file"
>> diff --git a/fs/ncpfs/mmap.c b/fs/ncpfs/mmap.c
>> index a7c07b4..e5d71b2 100644
>> --- a/fs/ncpfs/mmap.c
>> +++ b/fs/ncpfs/mmap.c
>> @@ -16,6 +16,7 @@
>>  #include <linux/mman.h>
>>  #include <linux/string.h>
>>  #include <linux/fcntl.h>
>> +#include <linux/memcontrol.h>
>>
>>  #include <asm/uaccess.h>
>>  #include <asm/system.h>
>> @@ -92,6 +93,7 @@ static int ncp_file_mmap_fault(struct vm_area_struct *area,
>>         * -- wli
>>         */
>>        count_vm_event(PGMAJFAULT);
>> +       mem_cgroup_count_vm_event(area->vm_mm, PGMAJFAULT);
>>        return VM_FAULT_MAJOR;
>>  }
>>
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index 5a5ce70..45e5268 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -24,6 +24,7 @@ struct mem_cgroup;
>>  struct page_cgroup;
>>  struct page;
>>  struct mm_struct;
>> +enum vm_event_item;
>>
>>  /* Stats that can be updated by kernel. */
>>  enum mem_cgroup_page_stat_item {
>> @@ -147,6 +148,9 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
>>                                                gfp_t gfp_mask);
>>  u64 mem_cgroup_get_limit(struct mem_cgroup *mem);
>>
>> +void mem_cgroup_pgfault(struct mem_cgroup *memcg, int val);
>> +void mem_cgroup_pgmajfault(struct mem_cgroup *memcg, int val);
>
> Do we have to expose above two functions?
> Isn't it enough to only mem_cgroup_count_vm_event?

probably not. will send another patch.

thanks
--Ying
>
>> +void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);
>
>
> --
> Kind regards,
> Minchan Kim
>

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