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Subject: Re: [PATCH 0/3] allow zram to use zbud as underlying allocator
To: Vitaly Wool <vitalywool@gmail.com>, Minchan Kim <minchan@kernel.org>
References: <20150914154901.92c5b7b24e15f04d8204de18@gmail.com>
 <20150915061349.GA16485@bbox>
 <CAMJBoFM_bMvQthAJPK+w4uQznqp7eFLdk=c7ZtT-R1aoF-1SeA@mail.gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Dan Streetman <ddstreet@ieee.org>, LKML <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        =?UTF-8?B?6rmA7KSA7IiY?= <iamjoonsoo.kim@lge.com>,
        Gioh Kim <gioh.kim@lge.com>
From: Vlastimil Babka <vbabka@suse.cz>
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Date: Wed, 30 Sep 2015 17:37:35 +0200
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On 09/25/2015 11:54 AM, Vitaly Wool wrote:
> Hello Minchan,
>
> the main use case where I see unacceptably long stalls in UI with
> zsmalloc is switching between users in Android.
> There is a way to automate user creation and switching between them so
> the test I run both to get vmstat statistics and to profile stalls is
> to create a user, switch to it and switch back. Each test cycle does
> that 10 times, and all the results presented below are averages for 20
> runs.
>
> Kernel configurations used for testing:
>
> (1): vanilla
> (2): (1) plus "make SLUB atomic" patch [1]
> (3): (1) with zbud instead of zsmalloc
> (4): (2) with compaction defer logic mostly disabled

Disabling compaction deferring leads to less compaction stalls? That 
indeed looks very weird and counter-intuitive. Also what's "mostly" 
disabled mean?