From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752016AbbGMXgN (ORCPT ); Mon, 13 Jul 2015 19:36:13 -0400 Received: from mail-pa0-f44.google.com ([209.85.220.44]:35574 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751507AbbGMXgL (ORCPT ); Mon, 13 Jul 2015 19:36:11 -0400 Date: Tue, 14 Jul 2015 08:36:02 +0900 From: Minchan Kim To: Sergey Senozhatsky Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: Re: [PATCH 0/3] zsmalloc: small compaction improvements Message-ID: <20150713233602.GA31822@blaptop.AC68U> References: <1436607932-7116-1-git-send-email-sergey.senozhatsky@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1436607932-7116-1-git-send-email-sergey.senozhatsky@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Sergey, On Sat, Jul 11, 2015 at 06:45:29PM +0900, Sergey Senozhatsky wrote: > Hello, > > First two patches introduce new zsmalloc zs_pages_to_compact() > symbol and change zram's `compact' sysfs attribute to be > read-write: > -- write triggers compaction, no changes > -- read returns the number of pages that compaction can > potentially free > > This lets user space to make a bit better decisions and to > avoid unneeded (which will not result in any significant > memory savings) compaction calls: > > Example: > > if [ `cat /sys/block/zram/compact` -gt 10 ]; then > echo 1 > /sys/block/zram/compact; > fi > > Up until now user space could not tell whether compaction > will result in any gain. First of all, thanks for the looking this. Question: What is motivation? IOW, did you see big overhead by user-triggered compaction? so, do you want to throttle it by userspace? > > The third patch removes class locking around zs_can_compact() > in zs_pages_to_compact(), the motivation and details are > provided in the commit message. > > Sergey Senozhatsky (3): > zsmalloc: factor out zs_pages_to_compact() > zram: make compact a read-write sysfs node > zsmalloc: do not take class lock in zs_pages_to_compact() > > Documentation/ABI/testing/sysfs-block-zram | 7 +++--- > Documentation/blockdev/zram.txt | 4 +++- > drivers/block/zram/zram_drv.c | 16 ++++++++++++- > include/linux/zsmalloc.h | 1 + > mm/zsmalloc.c | 37 +++++++++++++++++------------- > 5 files changed, 44 insertions(+), 21 deletions(-) > > -- > 2.4.5 > -- Kind regards, Minchan Kim