From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3202C433F5 for ; Fri, 25 Mar 2022 20:10:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4F2636B0071; Fri, 25 Mar 2022 16:10:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 47A7B6B0073; Fri, 25 Mar 2022 16:10:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 31D396B0074; Fri, 25 Mar 2022 16:10:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id 2085F6B0071 for ; Fri, 25 Mar 2022 16:10:03 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id DF9B720CCD for ; Fri, 25 Mar 2022 20:10:02 +0000 (UTC) X-FDA: 79283999844.10.7C828A5 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf15.hostedemail.com (Postfix) with ESMTP id 56570A002C for ; Fri, 25 Mar 2022 20:10:02 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 5F4CBB81DEA; Fri, 25 Mar 2022 20:10:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BB724C2BBE4; Fri, 25 Mar 2022 20:09:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1648238999; bh=U2Xz6H5GsLYeqmn4jr1ke0X4acjwp3OmRTeYeHGc3og=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=qIvWa0w2vkbg7NoLId8mtNnMM2KFz4vLiIUfQGPDyBWmTYMleT201nxKQlnkIMfrD nMzYvJJdR3+8oDL0okhiKxooKLgd++ecqffLSx6MRPc2POnA6vOd6HPmJsnyGo46+g CvZEXq+gi2H1jYEGTW/Y4T4jf3pCD3rgs8OgCHqA= Date: Fri, 25 Mar 2022 13:09:57 -0700 From: Andrew Morton To: cgel.zte@gmail.com Cc: david@redhat.com, yang.yang29@zte.com.cn, ran.xiaokai@zte.com.cn, yang.shi@linux.alibaba.com, dave.hansen@linux.intel.com, minchan@kernel.org, saravanand@fb.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, xu xin Subject: Re: [PATCH v3] mm/vmstat: add events for ksm cow Message-Id: <20220325130957.171a68dee88118082ab841c5@linux-foundation.org> In-Reply-To: <20220324104332.2350482-1-yang.yang29@zte.com.cn> References: <20220324104332.2350482-1-yang.yang29@zte.com.cn> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: 4htyponixjrrrw6a76nujdgikj51ebuf Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=qIvWa0w2; dmarc=none; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.68.75 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 56570A002C X-HE-Tag: 1648239002-202885 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 24 Mar 2022 10:43:33 +0000 cgel.zte@gmail.com wrote: > From: Yang Yang > > Users may use ksm by calling madvise(, , MADV_MERGEABLE) when they want > to save memory, it's a tradeoff by suffering delay on ksm cow. Users can > get to know how much memory ksm saved by reading > /sys/kernel/mm/ksm/pages_sharing, but they don't know what's the costs > of ksm cow, and this is important of some delay sensitive tasks. > > So add ksm cow events to help users evaluate whether or how to use ksm. It's unclear (to me) how anyone will actually use this, how they will interpret the output. Some tutorial words added to Documentation/vm/ksm.rst would be helpful. While in there, please check for any other /proc/vmstat fields which we forgot to document. > --- a/include/linux/vm_event_item.h > +++ b/include/linux/vm_event_item.h > @@ -131,6 +131,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, > SWAP_RA_HIT, > #ifdef CONFIG_KSM > KSM_SWPIN_COPY, > + COW_KSM, I agree that this name looks unpleasingly backwards. Do we have an expectation that we actually will be adding more COW_* fields?