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

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Date:	Wed, 15 Jan 2014 10:11:06 +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>,
	Minchan Kim <minchan@...nel.org>
Subject: [PATCH v2 0/4]zram: locking redesign

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

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