From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 15676 invoked by alias); 13 Apr 2011 20:57:31 -0000 Received: (qmail 15666 invoked by uid 22791); 13 Apr 2011 20:57:30 -0000 X-SWARE-Spam-Status: No, hits=-2.1 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from smtp-out.google.com (HELO smtp-out.google.com) (74.125.121.67) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 13 Apr 2011 20:57:24 +0000 Received: from hpaq14.eem.corp.google.com (hpaq14.eem.corp.google.com [172.25.149.14]) by smtp-out.google.com with ESMTP id p3DKvNJN004935 for ; Wed, 13 Apr 2011 13:57:23 -0700 Received: from pvg12 (pvg12.prod.google.com [10.241.210.140]) by hpaq14.eem.corp.google.com with ESMTP id p3DKvK2j022821 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Wed, 13 Apr 2011 13:57:22 -0700 Received: by pvg12 with SMTP id 12so363187pvg.19 for ; Wed, 13 Apr 2011 13:57:20 -0700 (PDT) MIME-Version: 1.0 Received: by 10.142.61.9 with SMTP id j9mr2108342wfa.416.1302728240232; Wed, 13 Apr 2011 13:57:20 -0700 (PDT) Received: by 10.142.158.19 with HTTP; Wed, 13 Apr 2011 13:57:20 -0700 (PDT) In-Reply-To: References: <20110412184923.33F942225D6@jade.mtv.corp.google.com> Date: Wed, 13 Apr 2011 20:57:00 -0000 Message-ID: Subject: Re: [patch] Split Parse Timevar (issue4378056) From: Lawrence Crowl To: Richard Guenther Cc: Diego Novillo , reply@codereview.appspotmail.com, jason@redhat.com, gcc-patches@gcc.gnu.org Content-Type: text/plain; charset=ISO-8859-1 X-System-Of-Record: true X-IsSubscribed: yes Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org X-SW-Source: 2011-04/txt/msg01029.txt.bz2 On 4/13/11, Richard Guenther wrote: > On Apr 12, 2011 Diego Novillo wrote: > > On Apr 12, 2011 Lawrence Crowl wrote: > > > This patch provides more finer, more precise compile time > > > information. I sent an advisory mail some time ago, and it > > > was good then. Please confirm for trunk. > > > > The patch looks fine to me, but of course it's Jason the one > > you need an OK from. > > Pushing/popping timevars is not free. What's the compile-time > impact of this change (for -ftime-report, of course) - with small > timed regions, does it not just return garbage because of clock > precision issues and overhead of querying the clock iself? I don't think there is any significant compile-time impact. * The new phase timevars cover so much execution time as to have unnoticible overhead. * The new parser sub-timevars cover significant parsing work: function body, struct body, enum body, template instantiation, and overload resolution. With the exception of enum bodies, all are pretty heavyweight. The overhead might grow from unnoticible to insignificant. * In some cases, the patch replaces a push/pop with a start/stop. The performance difference between those routines is very small. * Most other timevar calls have not changed, they are doing what they did before, so no new overhead is introduced. * The remaining calls were redundant, and the patch removes them, so some existing overhead is removed. -- Lawrence Crowl