From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751966AbbCLFYk (ORCPT ); Thu, 12 Mar 2015 01:24:40 -0400 Received: from mail-pd0-f180.google.com ([209.85.192.180]:44431 "EHLO mail-pd0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751243AbbCLFYi (ORCPT ); Thu, 12 Mar 2015 01:24:38 -0400 Date: Thu, 12 Mar 2015 14:24:44 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , Sergey Senozhatsky , Andrew Morton , Nitin Gupta , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/6] new zram statistics reporting scheme Message-ID: <20150312052444.GC3508@swordfish> References: <1426000114-4471-1-git-send-email-sergey.senozhatsky@gmail.com> <20150312015558.GG10820@blaptop> <20150312021609.GA3508@swordfish> <20150312051106.GA20144@blaptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150312051106.GA20144@blaptop> 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 On (03/12/15 14:11), Minchan Kim wrote: > I think we don't need CONFIG_ZRAM_OLD_STATS. > For example, for mem_used_max, we could add pr_warn_once in > *mem_used_max_show* but not *mem_used_max_store*. so, old users will see > deprecated message when they try to *read* the vaule old stat while they > will write new value. > One or two year later, we could remove mem_used_max_show then everyone > should read the vaule /sys/block/zram0/mm_stat. > > > > > > cat /sys/block/zram/mem_used_max > > > cat /sys/block/zram/mm_stat | awk friend > > > > > > How about changing only writeable, not readable for duplicated stats > > > in /sys/block/zram? So, user will have writeable stat to set some > > > options in /sys/block/zram and readable stat to get some data in > > > /sys/block/zram/[io|mm]_stat if the stat is duplicated in both. > > > > Sorry, I probably didn't drink enough coffee today, can you please > > rephrase or give a trivial example? > > Sorry, I was vague. I meant users can read the vaule for > mem_used_max and mem_limit in two places(ie, /sys/block/zram/ > and /sys/block/zram/mm_stat). If we feel it's handy for user, > i am not against that. But if there is no reason, I want to > make /sys/block/zram/ stat write-only if it is possible stat > like mem_used_max. I guess It's easier rule for user. in a long term -- yes. duplication must go away. we provide [mm|io]_stat nodes to do stats show. so, -- RW will be downgraded to WO -- RO will be removed (I'm talking about those attrs that are currently visible in two places -- the original per-stat sysfs node and new [mm|io]_stat node). and this is what CONFIG_ZRAM_OLD_STATS was doing: downgrade of RW to WO, removal of some RO attrs. but I'd prefer to go with warn once plan and do this downgrade/removal manually two years later. -ss