linux-kernel - Re: [PATCH] zsmalloc: don't test shrinker_enabled in zs_shrinker

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Date:	Thu, 15 Oct 2015 19:35:27 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: [PATCH] zsmalloc: don't test shrinker_enabled in
 zs_shrinker_count()

On Thu, Oct 15, 2015 at 12:53:17PM +0900, Sergey Senozhatsky wrote:
> 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.

I misunderstood your description. I thought you wanted to remove
codes for disabling auto-compaction by user because I really don't
want it like same reason of VM's compaction. My bad.

You woke up my brain, I remember the reason.
Thanks.

Acked-by: Minchan Kim <minchan@...nel.org>
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