From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752370AbcL3JLW (ORCPT ); Fri, 30 Dec 2016 04:11:22 -0500 Received: from mx2.suse.de ([195.135.220.15]:43420 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751820AbcL3JLU (ORCPT ); Fri, 30 Dec 2016 04:11:20 -0500 Date: Fri, 30 Dec 2016 09:11:17 +0000 From: Mel Gorman To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , Johannes Weiner , Vlastimil Babka , Rik van Riel , LKML Subject: Re: [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Message-ID: <20161230091117.nkxn3bnhle3bofhw@suse.de> References: <20161228153032.10821-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20161228153032.10821-1-mhocko@kernel.org> User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 28, 2016 at 04:30:25PM +0100, Michal Hocko wrote: > Hi, > while debugging [1] I've realized that there is some room for > improvements in the tracepoints set we offer currently. I had hard times > to make any conclusion from the existing ones. The resulting problem > turned out to be active list aging [2] and we are missing at least two > tracepoints to debug such a problem. > > Some existing tracepoints could export more information to see _why_ the > reclaim progress cannot be made not only _how much_ we could reclaim. > The later could be seen quite reasonably from the vmstat counters > already. It can be argued that we are showing too many implementation > details in those tracepoints but I consider them way too lowlevel > already to be usable by any kernel independent userspace. I would be > _really_ surprised if anything but debugging tools have used them. > > Any feedback is highly appreciated. > There is some minor overhead introduced in some paths regardless of whether the tracepoints are active or not but I suspect it's negligible in the context of the overhead of reclaim in general so; Acked-by: Mel Gorman -- Mel Gorman SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f200.google.com (mail-wj0-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id 502016B0038 for ; Fri, 30 Dec 2016 04:11:21 -0500 (EST) Received: by mail-wj0-f200.google.com with SMTP id iq1so36504748wjb.1 for ; Fri, 30 Dec 2016 01:11:21 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id ho7si61489649wjb.275.2016.12.30.01.11.19 for (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 30 Dec 2016 01:11:19 -0800 (PST) Date: Fri, 30 Dec 2016 09:11:17 +0000 From: Mel Gorman Subject: Re: [PATCH 0/7] vm, vmscan: enahance vmscan tracepoints Message-ID: <20161230091117.nkxn3bnhle3bofhw@suse.de> References: <20161228153032.10821-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20161228153032.10821-1-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , Johannes Weiner , Vlastimil Babka , Rik van Riel , LKML On Wed, Dec 28, 2016 at 04:30:25PM +0100, Michal Hocko wrote: > Hi, > while debugging [1] I've realized that there is some room for > improvements in the tracepoints set we offer currently. I had hard times > to make any conclusion from the existing ones. The resulting problem > turned out to be active list aging [2] and we are missing at least two > tracepoints to debug such a problem. > > Some existing tracepoints could export more information to see _why_ the > reclaim progress cannot be made not only _how much_ we could reclaim. > The later could be seen quite reasonably from the vmstat counters > already. It can be argued that we are showing too many implementation > details in those tracepoints but I consider them way too lowlevel > already to be usable by any kernel independent userspace. I would be > _really_ surprised if anything but debugging tools have used them. > > Any feedback is highly appreciated. > There is some minor overhead introduced in some paths regardless of whether the tracepoints are active or not but I suspect it's negligible in the context of the overhead of reclaim in general so; Acked-by: Mel Gorman -- Mel Gorman 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