KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> writes:
> On Sun, 3 Oct 2010 23:57:58 -0700
> Greg Thelen <gthelen@xxxxxxxxxx> 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>
>
> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>
> a nitpick. see below.
>
>> ---
>> 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 */
>> +};
>> +
>> extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
>> struct list_head *dst,
>> unsigned long *scanned, int order,
>> @@ -121,7 +126,22 @@ static inline bool mem_cgroup_disabled(void)
>> return false;
>> }
>>
>> -void mem_cgroup_update_file_mapped(struct page *page, int val);
>> +void mem_cgroup_update_page_stat(struct page *page,
>> + enum mem_cgroup_write_page_stat_item idx,
>> + int val);
>> +
>> +static inline void mem_cgroup_inc_page_stat(struct page *page,
>> + enum mem_cgroup_write_page_stat_item idx)
>> +{
>> + mem_cgroup_update_page_stat(page, idx, 1);
>> +}
>> +
>> +static inline void mem_cgroup_dec_page_stat(struct page *page,
>> + enum mem_cgroup_write_page_stat_item idx)
>> +{
>> + mem_cgroup_update_page_stat(page, idx, -1);
>> +}
>> +
>> 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);
>> @@ -293,8 +313,13 @@ mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
>> {
>> }
>>
>> -static inline void mem_cgroup_update_file_mapped(struct page *page,
>> - int val)
>> +static inline void mem_cgroup_inc_page_stat(struct page *page,
>> + enum mem_cgroup_write_page_stat_item idx)
>> +{
>> +}
>> +
>> +static inline void mem_cgroup_dec_page_stat(struct page *page,
>> + enum mem_cgroup_write_page_stat_item idx)
>> {
>> }
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 512cb12..f4259f4 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -1592,7 +1592,9 @@ bool mem_cgroup_handle_oom(struct mem_cgroup *mem, gfp_t mask)
>> * possibility of race condition. If there is, we take a lock.
>> */
>>
>> -static void mem_cgroup_update_file_stat(struct page *page, int idx, int val)
>> +void mem_cgroup_update_page_stat(struct page *page,
>> + enum mem_cgroup_write_page_stat_item idx,
>> + int val)
>> {
>> struct mem_cgroup *mem;
>> struct page_cgroup *pc = lookup_page_cgroup(page);
>> @@ -1615,30 +1617,27 @@ static void mem_cgroup_update_file_stat(struct page *page, int idx, int val)
>> goto out;
>> }
>>
>> - this_cpu_add(mem->stat->count[idx], val);
>> -
>> switch (idx) {
>> - case MEM_CGROUP_STAT_FILE_MAPPED:
>> + case MEMCG_NR_FILE_MAPPED:
>> if (val > 0)
>> SetPageCgroupFileMapped(pc);
>> else if (!page_mapped(page))
>> ClearPageCgroupFileMapped(pc);
>> + idx = MEM_CGROUP_STAT_FILE_MAPPED;
>> break;
>> default:
>> BUG();
>> }
>>
>> + this_cpu_add(mem->stat->count[idx], val);
>> +
>
> Why you move this_cpu_add() placement ?
> (This placement is ok but I just wonder..)
>
> Thanks,
> -Kame
The reason this_cpu_add() is moved to after the switch is because the
switch is needed to convert the input parameter from an enum
mem_cgroup_write_page_stat_item (example: MEMCG_NR_FILE_MAPPED) to enum
mem_cgroup_stat_index (example: MEM_CGROUP_STAT_FILE_MAPPED) before
indexing into the count array.
Also in subsequent patches (in this series) "val" is updated depending
on page_cgroup flags before usage by this_cpu_add().
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