linux-kernel - Re: [PATCH v2 0/4]zram: locking redesign

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Message-ID: <20140115012948.GE1992@bbox>
Date:	Wed, 15 Jan 2014 10:29:48 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, Nitin Gupta <ngupta@...are.org>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Jerome Marchand <jmarchan@...hat.com>
Subject: Re: [PATCH v2 0/4]zram: locking redesign

On Wed, Jan 15, 2014 at 10:11:06AM +0900, Minchan Kim wrote:
> Currently, zram->lock rw_semaphore is coarse-grained so it hurts
> for scalability.
> This patch try to enhance it with remove the lock in read path.
> 
> [1] uses atomic opeartion so it removes dependency of 32bit stat
> from zram->lock.
> [2] introduces table own lock instead of relying on zram->lock.
> [3] remove free pending slot mess so it makes core very clean.
> [4] finally removes zram->lock in read path and changes it with mutex.
> 
> So, output is wonderful. read/write mixed workload performs well
> 11 times than old and write concurrency is also enhanced because
> mutex supports SPIN_ON_OWNER while rw_semaphore doesn't yet.
> (I know recenty there were some effort to enhance it for rw_semaphore
> from Tim Chen but not sure it got merged. Anyway, we don't need it
> any more and there is no reason to prevent read-write concurrency)
> 
> Thanks.
> 
> Minchan Kim (4):
>   [1] zram: use atomic operation for stat
>   [2] zram: introduce zram->tb_lock
>   [3] zram: remove workqueue for freeing removed pending slot
>   [4] zram: Remove zram->lock in read path and change it with mutex
> 
>  drivers/staging/zram/zram_drv.c | 117 ++++++++++++++++------------------------
>  drivers/staging/zram/zram_drv.h |  27 +++-------
>  2 files changed, 51 insertions(+), 93 deletions(-)
> 
> -- 
> 1.8.5.2
> 

Oops, I missed Tested-by from Sergey. Really, sorry.
If I have a chance to resend from any review, I will add. Otherwise,
Andrew, Could you add his tested-by?

This patch is same with v1.
I just updated description from Andrew and Jerome's comment.

-- 
Kind regards,
Minchan Kim
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