From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Elisp native profiler Date: Mon, 01 Oct 2012 23:41:10 -0700 Organization: UCLA Computer Science Department Message-ID: <506A8C86.5010102@cs.ucla.edu> References: <5069CA0D.1080801@cs.ucla.edu> <1349123390.31932.1@faina> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1349160100 17092 80.91.229.3 (2 Oct 2012 06:41:40 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 2 Oct 2012 06:41:40 +0000 (UTC) Cc: Emacs Development To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Oct 02 08:41:42 2012 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1TIwAT-0005Iz-Dt for ged-emacs-devel@m.gmane.org; Tue, 02 Oct 2012 08:41:21 +0200 Original-Received: from localhost ([::1]:45044 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TIwAN-0004xh-QA for ged-emacs-devel@m.gmane.org; Tue, 02 Oct 2012 02:41:15 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:49355) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TIwAK-0004xa-T0 for Emacs-devel@gnu.org; Tue, 02 Oct 2012 02:41:13 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TIwAJ-0007dW-VH for Emacs-devel@gnu.org; Tue, 02 Oct 2012 02:41:12 -0400 Original-Received: from smtp.cs.ucla.edu ([131.179.128.62]:33986) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TIwAJ-0007dO-Pv for Emacs-devel@gnu.org; Tue, 02 Oct 2012 02:41:11 -0400 Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp.cs.ucla.edu (Postfix) with ESMTP id 10D3AA60003; Mon, 1 Oct 2012 23:41:11 -0700 (PDT) X-Virus-Scanned: amavisd-new at smtp.cs.ucla.edu Original-Received: from smtp.cs.ucla.edu ([127.0.0.1]) by localhost (smtp.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id SUODe3KgtF8W; Mon, 1 Oct 2012 23:41:10 -0700 (PDT) Original-Received: from [192.168.1.3] (pool-108-23-119-2.lsanca.fios.verizon.net [108.23.119.2]) by smtp.cs.ucla.edu (Postfix) with ESMTPSA id A6F75A60001; Mon, 1 Oct 2012 23:41:10 -0700 (PDT) User-Agent: Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20120912 Thunderbird/15.0.1 In-Reply-To: <1349123390.31932.1@faina> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-Received-From: 131.179.128.62 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:153892 Archived-At: On 10/01/2012 01:29 PM, Stefan Monnier wrote: > If it's common for 1ms to suffer from significant delays, > then it's a good argument for setting the default higher. I did a bit more investigation on this, on my host (x86-64, AMD Phenom II X4 910e, Fedora 17). I instrumented trunk bzr 110342 to count total timer overruns, and did a CPU benchmark that took about 15.6 seconds when not profiling. With a 10 ms profiling interval, there were zero overruns and the benchmark took 15.62 seconds, essentially full speed. With a 1 ms interval, there were 65 overruns and the benchmark took 51.52 seconds, a worse than 3x slowdown. With an 0.1 ms interval, there were 466,644 overruns and the benchmark took 52.12 seconds. It appears that the effective interval was closer to 1 ms than to 0.1 ms, as most of the samples were overrun. These numbers suggest that we should go with a 10 ms interval, at least for this kind of host.