From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751181AbdAMHCf (ORCPT ); Fri, 13 Jan 2017 02:02:35 -0500 Received: from mail-pf0-f193.google.com ([209.85.192.193]:35806 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbdAMHCe (ORCPT ); Fri, 13 Jan 2017 02:02:34 -0500 Date: Fri, 13 Jan 2017 16:02:45 +0900 From: Sergey Senozhatsky To: Minchan Kim Cc: Sergey Senozhatsky , zhouxianrong@huawei.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, sergey.senozhatsky@gmail.com, ngupta@vflare.org, Mi.Sophia.Wang@huawei.com, zhouxiyu@huawei.com, weidu.du@huawei.com, zhangshiming5@huawei.com, won.ho.park@huawei.com Subject: Re: [PATCH] mm: extend zero pages to same element pages for zram Message-ID: <20170113070245.GB484@jagdpanzerIV.localdomain> References: <1483692145-75357-1-git-send-email-zhouxianrong@huawei.com> <20170109234110.GA10298@bbox> <20170113042444.GE9360@jagdpanzerIV.localdomain> <20170113062343.GA7827@bbox> <20170113063614.GA484@jagdpanzerIV.localdomain> <20170113064719.GA8018@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170113064719.GA8018@bbox> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (01/13/17 15:47), Minchan Kim wrote: [..] > > > Could you elaborate a bit? Do you mean this? > > > > > > ret = scnprintf(buf, PAGE_SIZE, > > > "%8llu %8llu %8llu %8lu %8ld %8llu %8lu\n", > > > orig_size << PAGE_SHIFT, > > > (u64)atomic64_read(&zram->stats.compr_data_size), > > > mem_used << PAGE_SHIFT, > > > zram->limit_pages << PAGE_SHIFT, > > > max_used << PAGE_SHIFT, > > > // (u64)atomic64_read(&zram->stats.zero_pages), > > > (u64)atomic64_read(&zram->stats.same_pages), > > > pool_stats.pages_compacted); > > > > yes, correct. > > > > do we need to export it as two different stats (zero_pages and > > same_pages), if those are basically same thing internally? > > So, let summary up. > > 1. replace zero_page stat into same page stat in mm_stat > 2. s/zero_pages/same_pages/Documentation/blockdev/zram.txt > 3. No need to warn to "cat /sys/block/zram0/mm_stat" user to see zero_pages > about semantic change 1) account zero_page and same_pages in one attr. this already is in the patch. 2) do not rename zero_pages attr. we can't do this so fast, I think. > 3. No need to warn to "cat /sys/block/zram0/mm_stat" user to see zero_pages > about semantic change yes. we just _may_ have more pages (depending on data pattern) which we treat as "zero" pages internally. this results in lower memory consumption. I don't think warn users about this change is necessary; they won't be able to do anything about it anyway. zero_pages stat is pretty much just a fun number to know. isn't it? or do you think that we should account it in separate stats? -ss