linux-kernel - Re: [PATCH] zram: update zram to use zpool

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Message-ID: <CAMJBoFPcaAbsQ=PA2WPsmuyd1a-SyJgE5k4Rn2CUf6rS0-ykKw@mail.gmail.com>
Date:	Fri, 17 Jun 2016 10:30:58 +0200
From:	Vitaly Wool <vitalywool@...il.com>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Geliang Tang <geliangtang@...il.com>,
	Nitin Gupta <ngupta@...are.org>,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Dan Streetman <ddstreet@...e.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux-MM <linux-mm@...ck.org>
Subject: Re: [PATCH] zram: update zram to use zpool

Hi Minchan,

On Thu, Jun 16, 2016 at 1:17 AM, Minchan Kim <minchan@...nel.org> wrote:
> On Wed, Jun 15, 2016 at 10:42:07PM +0800, Geliang Tang wrote:
>> Change zram to use the zpool api instead of directly using zsmalloc.
>> The zpool api doesn't have zs_compact() and zs_pool_stats() functions.
>> I did the following two things to fix it.
>> 1) I replace zs_compact() with zpool_shrink(), use zpool_shrink() to
>>    call zs_compact() in zsmalloc.
>> 2) The 'pages_compacted' attribute is showed in zram by calling
>>    zs_pool_stats(). So in order not to call zs_pool_state() I move the
>>    attribute to zsmalloc.
>>
>> Signed-off-by: Geliang Tang <geliangtang@...il.com>
>
> NACK.
>
> I already explained why.
> http://lkml.kernel.org/r/20160609013411.GA29779@bbox

This is a fair statement, to a certain extent. I'll let Geliang speak
for himself but I am personally interested in this zram extension
because I want it to work on MMU-less systems. zsmalloc can not handle
that, so I want to be able to use zram over z3fold.

Best regards,
   Vitaly