From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752653AbbCLB4I (ORCPT ); Wed, 11 Mar 2015 21:56:08 -0400 Received: from mail-pa0-f49.google.com ([209.85.220.49]:46514 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752551AbbCLB4F (ORCPT ); Wed, 11 Mar 2015 21:56:05 -0400 Date: Thu, 12 Mar 2015 10:55:58 +0900 From: Minchan Kim To: Sergey Senozhatsky Cc: Andrew Morton , Nitin Gupta , linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: Re: [PATCH 0/6] new zram statistics reporting scheme Message-ID: <20150312015558.GG10820@blaptop> References: <1426000114-4471-1-git-send-email-sergey.senozhatsky@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1426000114-4471-1-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 Hi Sergey, On Wed, Mar 11, 2015 at 12:08:28AM +0900, Sergey Senozhatsky wrote: > Hello, > > This patch introduces rework to zram stats. We have per-stat sysfs > nodes, and it makes things a bit hard to use in user space: it doesn't > give an immediate stats 'snapshot', it requires user space to use > more syscals -- open, read, close for every stat file, with > appropriate error checks on every step, etc. > > First, zram now accounts block layer statistics. available in > /sys/block/zram/stat and /proc/diskstats files. So some new > stats are available (see Documentation/block/stat.txt), besides, > zram's activities are now can be monitored by sysstat's iostat > or similar tools. > > Example: > cat /sys/block/zram0/stat > 248 0 1984 0 251029 0 2008232 5120 0 5116 5116 > > > > Second, group currently exported on per-stat basis nodes into two > categories (files): > > -- zram/io_stat > accumulates device's IO stats, that are not accounted by block layer, > and contains: > failed_reads > failed_writes > invalid_io > notify_free > > Example: > cat /sys/block/zram0/io_stat > 0 0 0 652572 > > > -- zram/mm_stat > accumulates zram mm stats and contains: > orig_data_size > compr_data_size > mem_used_total > mem_limit > mem_used_max > zero_pages > num_migrated > > Example: > cat /sys/block/zram0/mm_stat > 434634752 270288572 279158784 0 579895296 15060 0 > > > per-stat sysfs nodes are now considered to be deprecated and we plan > to remove them (and clean up some of the existing stat code) in two > years (as of now, there is no warning printed to syslog about deprecated > stats being used). user space is advised to use the above mentioned 3 > files. > > > note: > util-linux mailing list is not Cc-ed into this series. once we settle > it down, I'll write to Karel. (we have several months ahead until 4.1 > will be released). I really appreciate you enhance stat functions, esp, working with iostat! One thing I want to discuss is sometime we could remove RO fields in /sys/block/zram/ but we couldn't remove RW fields because io_stat/mm_stat doesn't have any writable option now so users will have two options to read stat. For exmaple, 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. -- Kind regards, Minchan Kim