linux-kernel - Re: [RFC][PATCHv3 3/7] zsmalloc: always keep per-class stats

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Date:	Mon, 29 Jun 2015 18:06:34 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Subject: Re: [RFC][PATCHv3 3/7] zsmalloc: always keep per-class stats

On (06/29/15 15:40), Minchan Kim wrote:
> On Thu, Jun 18, 2015 at 08:46:40PM +0900, Sergey Senozhatsky wrote:
> > Always account per-class `zs_size_stat' stats. This data will
> > help us make better decisions during compaction. We are especially
> > interested in OBJ_ALLOCATED and OBJ_USED, which can tell us if
> > class compaction will result in any memory gain.
> > 
> > For instance, we know the number of allocated objects in the class,
> > the number of objects being used (so we also know how many objects
> > are not used) and the number of objects per-page. So we can ensure
> > if we have enough unused objects to form at least one ZS_EMPTY
> > zspage during compaction.
> > 
> > We calculate this value on per-class basis so we can calculate a
> > total number of zspages that can be released. Which is exactly what
> > a shrinker wants to know.
> > 
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> Acked-by: Minchan Kim <minchan@...nel.org>
> 

thanks.

	-ss
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