linux-kernel - Re: zram: per-cpu compression streams

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Message-ID: <20160427081059.GA429@swordfish>
Date:	Wed, 27 Apr 2016 17:10:59 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: Re: zram: per-cpu compression streams

On (04/27/16 16:55), Minchan Kim wrote:
[..]
> > > Could you test concurrent mem hogger with fio rather than pre-fault before fio test
> > > in next submit?
> > 
> > this test will not prove anything, unfortunately. I performed it;
> > and it's impossible to guarantee even remotely stable results.
> > mem-hogger process can spend on pre-fault from 41 to 81 seconds;
> > so I'm quite sceptical about the actual value of this test.
> > 
> > > > considering buffer_compress_percentage=11, the box was under somewhat
> > > > heavy pressure.
> > > > 
> > > > now, the results
> > > 
> > > Yeb, Even, recompression case is fater than old but want to see more heavy memory
> > > pressure case and the ratio I mentioned above.
> > 
> > I did quite heavy testing over the last 7 days, with numerous OOM kills
> > and OOM panics.
> 
> Okay, I think it's worth to merge enough and see the result.
> Please send formal patch which has recompression stat. ;-)


correction: those 41-81s spikes in mem-hogger were observed under
different scenario: 10GB zram with 6GB mem-hogger on a 4GB system.

I'll do another round of tests (with parallel mem-hogger pre-fault
and 4GB/4GB zram/mem-hogger split) and collect the number that you
asked for.

thanks!

	-ss