linux-kernel - Re: [PATCH v5 5/7] zsmalloc/zram: store compaction stats in zspool

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Date:	Mon, 6 Jul 2015 23:01:52 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, sergey.senozhatsky.work@...il.com
Subject: Re: [PATCH v5 5/7] zsmalloc/zram: store compaction stats in zspool

On Mon, Jul 06, 2015 at 10:56:46PM +0900, Sergey Senozhatsky wrote:
> On (07/06/15 22:27), Minchan Kim wrote:
> > > `zs_compact_control' accounts the number of migrated objects but
> > > it has a limited lifespan -- we lose it as soon as zs_compaction()
> > > returns back to zram. It was fine, because (a) zram had it's own
> > > counter of migrated objects and (b) only zram could trigger
> > > compaction. However, this does not work for automatic pool
> > > compaction (not issued by zram). To account objects migrated
> > > during auto-compaction (issued by the shrinker) we need to store
> > > this number in zs_pool.
> > > 
> > > A new zsmalloc zs_get_num_migrated() symbol exports zs_pool's
> > > ->num_migrated counter, so we better start using it, rather than
> > > continue keeping zram's own `num_migrated' copy in zram_stats.
> > 
> > If we introduce like this API we should make new another API when
> > we want to introduce new stats. So I don't think it's a good idea.
> > How about this?
> > 
> >         void zsmalloc_stats(struct zsmalloc_stats *stats);
> > 
> > So, we could return any upcoming stats without new API introduce.
> > 
> 
> Hm, agree. Do you prefer me to fold this into this patch set or to do as
> a separate work later?

Let's fold it so your next patch can use it for getting num_compacted.

> 
> 
> P.S.
> 
> Sorry. Seems that my git send-email has some problems, so group-reply
> in mutt does not work as expected.
> 
> 
> 	-ss

-- 
Kind regards,
Minchan Kim
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