Minchan Kim <minchan.kim@xxxxxxxxx> writes:
> On Sun, Oct 03, 2010 at 11:57:58PM -0700, Greg Thelen wrote:
>> Replace usage of the mem_cgroup_update_file_mapped() memcg
>> statistic update routine with two new routines:
>> * mem_cgroup_inc_page_stat()
>> * mem_cgroup_dec_page_stat()
>>
>> As before, only the file_mapped statistic is managed. However,
>> these more general interfaces allow for new statistics to be
>> more easily added. New statistics are added with memcg dirty
>> page accounting.
>>
>> Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
>> Signed-off-by: Andrea Righi <arighi@xxxxxxxxxxx>
>> ---
>> include/linux/memcontrol.h | 31 ++++++++++++++++++++++++++++---
>> mm/memcontrol.c | 17 ++++++++---------
>> mm/rmap.c | 4 ++--
>> 3 files changed, 38 insertions(+), 14 deletions(-)
>>
>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>> index 159a076..7c7bec4 100644
>> --- a/include/linux/memcontrol.h
>> +++ b/include/linux/memcontrol.h
>> @@ -25,6 +25,11 @@ struct page_cgroup;
>> struct page;
>> struct mm_struct;
>>
>> +/* Stats that can be updated by kernel. */
>> +enum mem_cgroup_write_page_stat_item {
>> + MEMCG_NR_FILE_MAPPED, /* # of pages charged as file rss */
>> +};
>> +
>
> mem_cgrou_"write"_page_stat_item?
> Does "write" make sense to abstract page_state generally?
First I will summarize the portion of the design relevant to this
comment:
This patch series introduces two sets of memcg statistics.
a) the writable set of statistics the kernel updates when pages change
state (example: when a page becomes dirty) using:
mem_cgroup_inc_page_stat(struct page *page,
enum mem_cgroup_write_page_stat_item idx)
mem_cgroup_dec_page_stat(struct page *page,
enum mem_cgroup_write_page_stat_item idx)
b) the read-only set of statistics the kernel queries to measure the
amount of dirty memory used by the current cgroup using:
s64 mem_cgroup_page_stat(enum mem_cgroup_read_page_stat_item item)
This read-only set of statistics is set of a higher level conceptual
counters. For example, MEMCG_NR_DIRTYABLE_PAGES is the sum of the
counts of pages in various states (active + inactive). mem_cgroup
exports this value as a higher level counter rather than individual
counters (active & inactive) to minimize the number of calls into
mem_cgroup_page_stat(). This avoids extra calls to cgroup tree
iteration with for_each_mem_cgroup_tree().
Notice that each of the two sets of statistics are addressed by a
different type, mem_cgroup_{read vs write}_page_stat_item.
This particular patch (memcg: create extensible page stat update
routines) introduces part of this design. A later patch I emailed
(memcg: add dirty limits to mem_cgroup) added
mem_cgroup_read_page_stat_item.
I think the code would read better if I renamed
enum mem_cgroup_write_page_stat_item to
enum mem_cgroup_update_page_stat_item.
Would this address your concern?
--
Greg
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