From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f72.google.com (mail-pa0-f72.google.com [209.85.220.72]) by kanga.kvack.org (Postfix) with ESMTP id C2C236B0253 for ; Thu, 28 Jul 2016 16:11:28 -0400 (EDT) Received: by mail-pa0-f72.google.com with SMTP id ca5so67949734pac.0 for ; Thu, 28 Jul 2016 13:11:28 -0700 (PDT) Received: from mail-pa0-x243.google.com (mail-pa0-x243.google.com. [2607:f8b0:400e:c03::243]) by mx.google.com with ESMTPS id xz3si13859974pab.244.2016.07.28.13.11.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Jul 2016 13:11:27 -0700 (PDT) Received: by mail-pa0-x243.google.com with SMTP id ez1so4009751pab.3 for ; Thu, 28 Jul 2016 13:11:27 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2104\)) Subject: Re: [PATCH 1/2] mm: page_alloc.c: Add tracepoints for slowpath From: Janani Ravichandran In-Reply-To: <20160727112303.11409a4e@gandalf.local.home> Date: Fri, 29 Jul 2016 01:41:20 +0530 Content-Transfer-Encoding: quoted-printable Message-Id: <0AF03F78-AA34-4531-899A-EA1076B6B3A1@gmail.com> References: <6b12aed89ad75cb2b3525a24265fa1d622409b42.1469629027.git.janani.rvchndrn@gmail.com> <20160727112303.11409a4e@gandalf.local.home> Sender: owner-linux-mm@kvack.org List-ID: To: Steven Rostedt Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, riel@surriel.com, akpm@linux-foundation.org, hannes@compxchg.org, vdavydov@virtuozzo.com, mhocko@suse.com, vbabka@suse.cz, mgorman@techsingularity.net, kirill.shutemov@linux.intel.com, bywxiaobai@163.com > On Jul 27, 2016, at 8:53 PM, Steven Rostedt = wrote: >=20 > I'm thinking you only need one tracepoint, and use function_graph > tracer for the length of the function call. >=20 > # cd /sys/kernel/debug/tracing > # echo __alloc_pages_nodemask > set_ftrace_filter > # echo function_graph > current_tracer > # echo 1 > events/kmem/trace_mm_slowpath/enable Thank you so much for your feedback!=20 Actually, the goal is to only single out those cases with latencies = higher than a given threshold. So, in accordance with this, I added those begin/end tracepoints and = thought I=20 could use a script to read the output of trace_pipe and only write to = disk the trace=20 information associated with latencies above the threshold. This would = help prevent=20 high disk I/O, especially when the threshold set is high. I looked at function graph trace, as you=E2=80=99d suggested. I saw that = I could set a threshold=20 there using tracing_thresh. But the problem was that slowpath trace = information was printed for all the cases (even when __alloc_pages_nodemask latencies were below = the threshold). Is there a way to print tracepoint information only when = __alloc_pages_nodemask exceeds the threshold? Thanks! Janani. >=20 > -- Steve >=20 >=20 >> return page; >> } >>=20 >=20 -- 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