From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: master afc0bfd380: Speed up loaddefs-generate on slow disks Date: Fri, 03 Jun 2022 08:21:32 -0400 Message-ID: References: <165416120601.23485.9799765950267646757@vcs2.savannah.gnu.org> <20220602091326.514E9C009A8@vcs2.savannah.gnu.org> <87a6avccs4.fsf@gnus.org> <83r147dosf.fsf@gnu.org> <838rqee1k4.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="19831"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) Cc: larsi@gnus.org, emacs-devel@gnu.org, eggert@cs.ucla.edu To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Jun 03 14:22:30 2022 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nx6Jx-0004vX-Nf for ged-emacs-devel@m.gmane-mx.org; Fri, 03 Jun 2022 14:22:29 +0200 Original-Received: from localhost ([::1]:40314 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nx6Jw-0008NT-8C for ged-emacs-devel@m.gmane-mx.org; Fri, 03 Jun 2022 08:22:28 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:52360) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nx6JA-00070U-4d for emacs-devel@gnu.org; Fri, 03 Jun 2022 08:21:40 -0400 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]:14177) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nx6J7-0005bk-LH; Fri, 03 Jun 2022 08:21:39 -0400 Original-Received: from pmg1.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id BE941100054; Fri, 3 Jun 2022 08:21:35 -0400 (EDT) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id 23B57100442; Fri, 3 Jun 2022 08:21:34 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1654258894; bh=o3cmxItNCXw5Xs4C24+9OAaB3FEvHiivLdf4B4rkCs8=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=FcP7c3CBo53x+KwVhm2P4g9CM6yE60buo4L23kxWGI9d6/cHo+9sbZjC+E6ipNXlc eYm1eVKO+Q8FDFS/o/lKXiA/H2gxuvjTG+Y8lg0hoxkMVvJjxwKHxleM3lDK8zm+ZB TsNV4KcYRiUCYBtQPW+uOGwW0FbzRdDxp8X9joWWpaFXTjfkKfJxBqJWuJsyllkRmL PHUrB9MNfWcxz/nJ1vabfylOrkiXAfidVfPTX2H8RFuUEvxMXRGahV2bwLLw9e4gMw +QAUvLc4U7msohWhgY/CDGLY1FHO03W3W89alSPCFWpyPZsk6YwTwDzRoXhG4Olpor 6RR1B8hL005dA== Original-Received: from pastel (unknown [45.72.221.51]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id E00EC1202F2; Fri, 3 Jun 2022 08:21:33 -0400 (EDT) In-Reply-To: <838rqee1k4.fsf@gnu.org> (Eli Zaretskii's message of "Fri, 03 Jun 2022 08:52:27 +0300") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:290618 Archived-At: >> This suggests that the kind of change I suggested would make it even >> a bit faster, tho it should reduce the run time by less than 50% >> under Windows (because the time to do the `stat`s is apparently already >> >50% of the total). > > I don't know how you deduce the 50% figure. The old code performed 2*N `stat`s. The new current code performs N times `time-less-p` and `file-attributes`, which is N `stat`s plus N times some overhead. The proposed new functionality would reduce this to more or less just N `stat`s so it would save us the "some overhead". Because the old code is slower than the current code, we know that 2*stat > stat + overhead thus `stat > overhead`. So `overhead` is less than 50% of `stat + overhead`. Stefan