linux-kernel - Re: [PATCH 0/3] zsmalloc: small compaction improvements

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Date:	Wed, 15 Jul 2015 09:24:00 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] zsmalloc: small compaction improvements

On Wed, Jul 15, 2015 at 09:21:06AM +0900, Sergey Senozhatsky wrote:
> On (07/15/15 01:52), Minchan Kim wrote:
> > > alrighty... again...
> > > 
> > > > > 
> > > > > /sys/block/zram<id>/compact is a black box. We provide it, we don't
> > > > > throttle it in the kernel, and user space is absolutely clueless when
> > > > > it invokes compaction. From some remote (or alternative) point of
> > > > 
> > > > But we have zs_can_compact so it can effectively skip the class if it
> > > > is not proper class.
> > > 
> > > user triggered compaction can compact too much.
> > > in its current state triggering a compaction from user space is like
> > > playing a lottery or a russian roulette.
> > 
> > We were on different page.
> 
> > I thought the motivation from this patchset is to prevent compaction
> > overhead by frequent user-driven compaction request because user
> > don't know how they can get free pages by compaction so they should
> > ask compact frequently with blind.
> 
> this is exactly the motivation for this patchset. seriously.

User should rely on the auto-compaction.

> 
> whatever.
> 
> 	-ss

-- 
Kind regards,
Minchan Kim
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