From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f71.google.com (mail-wm0-f71.google.com [74.125.82.71]) by kanga.kvack.org (Postfix) with ESMTP id D14636B0253 for ; Thu, 12 Jan 2017 03:15:59 -0500 (EST) Received: by mail-wm0-f71.google.com with SMTP id d140so1934183wmd.4 for ; Thu, 12 Jan 2017 00:15:59 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id es12si6343104wjb.42.2017.01.12.00.15.58 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 12 Jan 2017 00:15:58 -0800 (PST) Date: Thu, 12 Jan 2017 09:15:54 +0100 From: Michal Hocko Subject: Re: + mm-vmscan-add-mm_vmscan_inactive_list_is_low-tracepoint.patch added to -mm tree Message-ID: <20170112081554.GB2264@dhcp22.suse.cz> References: <586edadc.figmHAGrTxvM7Wei%akpm@linux-foundation.org> <20170110235250.GA7130@bbox> <20170111155239.GD16365@dhcp22.suse.cz> <20170112051247.GA8387@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170112051247.GA8387@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: linux-kernel@vger.kernel.org, hillf.zj@alibaba-inc.com, mgorman@suse.de, vbabka@suse.cz, mm-commits@vger.kernel.org, linux-mm@kvack.org On Thu 12-01-17 14:12:47, Minchan Kim wrote: > Hello, > > On Wed, Jan 11, 2017 at 04:52:39PM +0100, Michal Hocko wrote: > > On Wed 11-01-17 08:52:50, Minchan Kim wrote: > > [...] > > > > @@ -2055,8 +2055,8 @@ static bool inactive_list_is_low(struct > > > > if (!file && !total_swap_pages) > > > > return false; > > > > > > > > - inactive = lruvec_lru_size(lruvec, file * LRU_FILE); > > > > - active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE); > > > > + total_inactive = inactive = lruvec_lru_size(lruvec, file * LRU_FILE); > > > > + total_active = active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE); > > > > > > > > > > the decision of deactivating is based on eligible zone's LRU size, > > > not whole zone so why should we need to get a trace of all zones's LRU? > > > > Strictly speaking, the total_ counters are not necessary for making the > > decision. I found reporting those numbers useful regardless because this > > will give us also an information how large is the eligible portion of > > the LRU list. We do not have any other tracepoint which would report > > that. > > The patch doesn't say anything why it's useful. Could you tell why it's > useful and inactive_list_is_low should be right place? > > Don't get me wrong, please. I don't want to bother you. > I really don't want to add random stuff although it's tracepoint for > debugging. This doesn't sounds random to me. We simply do not have a full picture on 32b systems without this information. Especially when memcgs are involved and global numbers spread over different LRUs. > > [...] > > > > @@ -2223,7 +2228,7 @@ static void get_scan_count(struct lruvec > > > > * lruvec even if it has plenty of old anonymous pages unless the > > > > * system is under heavy pressure. > > > > */ > > > > - if (!inactive_list_is_low(lruvec, true, sc) && > > > > + if (!inactive_list_is_low(lruvec, true, sc, false) && > > > > > > Hmm, I was curious why you added trace boolean arguement and found it here. > > > Yes, here is not related to deactivation directly but couldn't we help to > > > trace it unconditionally? > > > > I've had it like that when I was debugging the mentioned bug and found > > it a bit disturbing. It generated more output than I would like and it > > wasn't really clear from which code path this has been called from. > > Indeed. > > Personally, I want to move inactive_list_is_low in shrink_active_list > and shrink_active_list calls inactive_list_is_low(...., true), > unconditionally so that it can make code simple/clear but cannot remove > trace boolean variable , which what I want. So, it's okay if you love > your version. I am not sure I am following. Why is the additional parameter a problem? -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org