Re: [PATCH] mm: account reaped page cache on inode cache pruning

[Konstantin Khlebnikov <khlebnikov@openvz.org>]

Andrew Morton wrote:
> On Wed, 16 Nov 2011 17:47:13 +0300
> Konstantin Khlebnikov<khlebnikov@openvz.org>  wrote:
>
>> Inode cache pruning indirectly reclaims page-cache by invalidating mapping pages.
>> Let's account them into reclaim-state to notice this progress in memory reclaimer.
>>
>> Signed-off-by: Konstantin Khlebnikov<khlebnikov@openvz.org>
>> ---
>>   fs/inode.c |    2 ++
>>   1 files changed, 2 insertions(+), 0 deletions(-)
>>
>> diff --git a/fs/inode.c b/fs/inode.c
>> index ee4e66b..1f6c48d 100644
>> --- a/fs/inode.c
>> +++ b/fs/inode.c
>> @@ -692,6 +692,8 @@ void prune_icache_sb(struct super_block *sb, int nr_to_scan)
>>   	else
>>   		__count_vm_events(PGINODESTEAL, reap);
>>   	spin_unlock(&sb->s_inode_lru_lock);
>> +	if (current->reclaim_state)
>> +		current->reclaim_state->reclaimed_slab += reap;
>>
>>   	dispose_list(&freeable);
>>   }
>
> hm, yes, I suppose we should.
>
> It seems to be cheating to use the "reclaimed_slab" field for this.
> Perhaps it would be cleaner to add an additional field to reclaim_state
> for non-slab pages which were also reclaimed.  That's a cosmetic thing
> and I guess we don't need to go that far, not sure...

Do we really need separate on-stack reclaim_state structure with single field?
Maybe replace it with single long (or even unsigned int) .reclaimed_pages field on task_struct
and account reclaimed pages unconditionally.

>
>