Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754759Ab0D1OrT (ORCPT ); Wed, 28 Apr 2010 10:47:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38978 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754709Ab0D1OrP (ORCPT ); Wed, 28 Apr 2010 10:47:15 -0400 Message-ID: <4BD84A27.6010504@redhat.com> Date: Wed, 28 Apr 2010 10:45:59 -0400 From: Masami Hiramatsu User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100330 Fedora/3.0.4-1.fc11 Thunderbird/3.0.4 MIME-Version: 1.0 To: Steven Rostedt CC: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Arnaldo Carvalho de Melo , Mathieu Desnoyers , Lai Jiangshan , Li Zefan , Christoph Hellwig Subject: Re: [PATCH 00/10][RFC] tracing: Lowering the footprint of TRACE_EVENTs References: <20100426195024.256424113@goodmis.org> In-Reply-To: <20100426195024.256424113@goodmis.org> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2019 Lines: 53 Steven Rostedt wrote: > This is an RFC patch set that also affects kprobes and perf. > > At the Linux Collaboration Summit, I talked with Mathieu and others about > lowering the footprint of trace events. I spent all of last week > trying to get the size as small as I could. > > Currently, each TRACE_EVENT() macro adds 1 - 5K per tracepoint. I got various > results by adding a TRACE_EVENT() with the compiler, depending on > config options that did not seem related. The new tracepoint I added > would add between 1 and 5K, but I did not investigate enough to > see what the true size was. > > What was consistent, was the DEFINE_EVENT(). Currently, it adds > a little over 700 bytes per DEFINE_EVENT(). > > This patch series does not seem to affect TRACE_EVENT() much (had > the same various sizes), but consistently brings DEFINE_EVENT()s > down from 700 bytes to 250 bytes per DEFINE_EVENT(). Since syscalls > use one "class" and are equivalent to DEFINE_EVENT() this can > be a significant savings. > > With events and syscalls (82 events and 616 syscalls), before this > patch series, the size of vmlinux was: 16161794, and afterward: 16058182. > > That is 103,612 bytes in savings! (over 100K) > > > Without tracing syscalls (82 events), it brought the size of vmlinux > down from 1591046 to 15999394. > > 22,071 bytes in savings. > > This is just an RFC (for now), to get peoples opinions on the changes. > It does a bit of rewriting of the CPP macros, just to warning you ;-) Hm, at least for kprobe tracer, this change is ok, even though it isn't much worth as for tracepoints. I think, if we have ftrace_event_ops, it will help reducing the size of dynamic events a bit (not so much). Thank you, -- Masami Hiramatsu e-mail: mhiramat@redhat.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/