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

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Message-ID: <20160427090139.GA1317@swordfish>
Date:	Wed, 27 Apr 2016 18:01:40 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	Minchan Kim <minchan@...nel.org>,
	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 17:54), Sergey Senozhatsky wrote:
> #jobs4                         	                
> READ:           19948MB/s	 20013MB/s
> READ:           17732MB/s	 17479MB/s
> WRITE:          630690KB/s	 495078KB/s
> WRITE:          1843.2MB/s	 2226.9MB/s
> READ:           1603.4MB/s	 1846.8MB/s
> WRITE:          1599.4MB/s	 1842.2MB/s
> READ:           1547.7MB/s	 1740.7MB/s
> WRITE:          1549.2MB/s	 1742.4MB/s

> jobs4
> stalled-cycles-frontend     265,519,049,536 (  64.46%)	  221,049,841,649 (  61.81%)
> stalled-cycles-backend      146,538,881,296 (  35.57%)	  113,774,053,039 (  31.82%)
> instructions                298,241,854,695 (    0.72)	  278,000,866,874 (    0.78)
> branches                     59,531,800,053 ( 400.919)	   55,096,944,109 ( 427.816)
> branch-misses                   285,108,083 (   0.48%)	      260,972,185 (   0.47%)

> seconds elapsed        47.816933840	52.966896478

per-cpu in general looks better in this test (jobs4): less stalls, less
branches, less misses, better fio speeds (except for WRITE: 630690KB/s  495078KB/s).
the system was under pressure, so quite possible that it took more time to kill the
process, thus execution time is in favor of 8 streams test.

	-ss