Re: [PATCH] zsmalloc: don't test shrinker_enabled in zs_shrinker_count()

[Sergey Senozhatsky]

On (10/15/15 11:29), Minchan Kim wrote:
[..]
> I'm in favor of removing shrinker disable feature with this patch(
> although we didn't implement it yet) because if there is some problem
> of compaction, we should reveal and fix it without hiding with the
> feature.
> 

sure.

> One thing I want is if we decide it, let's remove all things
> about shrinker_enabled(ie, variable).
> If we might need it later, we could introduce it easily.

well, do we really want to make the shrinker a vital part of zsmalloc?

it's not that we will tighten the dependency between zsmalloc and
shrinker, we will introduce it instead. in a sense that, at the moment,
zsmalloc is, let's say, ignorant to shrinker registration errors
(shrinker registration implementation is internal to shrinker), because
there is no direct impact on zsmalloc functionality -- zsmalloc will not
be able to release some pages (there are if-s here: first, zsmalloc
shrinker callback may even not be called; second, zsmalloc may not be
albe to migrate objects and release objects).

no really strong opinion against, but at the same time zsmalloc will
have another point of failure (again, zsmalloc should not be aware of
shrinker registration implementation and why it may fail).

so... I can prepare a new patch later today.

	-ss

> 
> > 
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
> > ---
> >  mm/zsmalloc.c | 3 ---
> >  1 file changed, 3 deletions(-)
> > 
> > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> > index 7ad5e54..8ba247d 100644
> > --- a/mm/zsmalloc.c
> > +++ b/mm/zsmalloc.c
> > @@ -1822,9 +1822,6 @@ static unsigned long zs_shrinker_count(struct shrinker *shrinker,
> >  	struct zs_pool *pool = container_of(shrinker, struct zs_pool,
> >  			shrinker);
> >  
> > -	if (!pool->shrinker_enabled)
> > -		return 0;
> > -
> >  	for (i = zs_size_classes - 1; i >= 0; i--) {
> >  		class = pool->size_class[i];
> >  		if (!class)
> > -- 
> > 2.6.1.134.g4b1fd35
> > 
> 
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