From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752828AbdKWNAL (ORCPT ); Thu, 23 Nov 2017 08:00:11 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:51082 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752644AbdKWNAK (ORCPT ); Thu, 23 Nov 2017 08:00:10 -0500 Subject: Re: [PATCH] Add slowpath enter/exit trace events To: peter.enderborg@sony.com, Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Steven Rostedt , Ingo Molnar , Alex Deucher , "David S . Miller" , Harry Wentland , Greg Kroah-Hartman , Tony Cheng , Andrew Morton , Vlastimil Babka , Mel Gorman , Johannes Weiner , Pavel Tatashin References: <20171123104336.25855-1-peter.enderborg@sony.com> From: Tetsuo Handa Message-ID: Date: Thu, 23 Nov 2017 22:00:04 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171123104336.25855-1-peter.enderborg@sony.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2017/11/23 19:43, peter.enderborg@sony.com wrote: > The warning of slow allocation has been removed, this is > a other way to fetch that information. But you need > to enable the trace. The exit function also returns > information about the number of retries, how long > it was stalled and failure reason if that happened. However, the fast path (I mean, get_page_from_freelist() at "/* First allocation attempt */" label) might be slow, for it is allowed to call node_reclaim() which can take uncontrollable duration. I think that you need to add hooks like http://lkml.kernel.org/r/1510833448-19918-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp does. ;-)