From owner-freebsd-stable@FreeBSD.ORG Sat Mar 21 00:28:16 2015 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 6B289B2D; Sat, 21 Mar 2015 00:28:16 +0000 (UTC) Received: from anubis.delphij.net (anubis.delphij.net [IPv6:2001:470:1:117::25]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "anubis.delphij.net", Issuer "StartCom Class 1 Primary Intermediate Server CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4A64D2DD; Sat, 21 Mar 2015 00:28:16 +0000 (UTC) Received: from zeta.ixsystems.com (unknown [12.229.62.2]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by anubis.delphij.net (Postfix) with ESMTPSA id E147FEC22; Fri, 20 Mar 2015 17:28:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=delphij.net; s=anubis; t=1426897695; x=1426912095; bh=o6TeM+geLGy/epHhr732ZlOcdO8yHX+TsbCIp2aTAwk=; h=Date:From:Reply-To:To:CC:Subject:References:In-Reply-To; b=H+f13EP4Vq1+/8ZUXQRcJP4C+woZ5Mg3Y0Nk76owzt0djjYsXh80mSwcl0x4f1DRC hql2D1KKJLUdERVUj401Gxk4ndW2FBKTk4ucFZYLTouK//K12HdamGNBv/TkcysyGb D43waDH/IBt3pjCPTxn2sOHFytY18tjxrU0Q0WPY= Message-ID: <550CBB1F.8010601@delphij.net> Date: Fri, 20 Mar 2015 17:28:15 -0700 From: Xin Li Reply-To: d@delphij.net Organization: The FreeBSD Project MIME-Version: 1.0 To: Konstantin Belousov , d@delphij.net Subject: Re: RELENG_10 performance regression (was Re: 35-40% performance drop releng9 vs releng10 openvpn References: <5506250A.2000506@sentex.net> <20150316132055.GQ32288@funkthat.com> <5509D6C6.4050204@sentex.net> <20150318211457.GL51048@funkthat.com> <550B6950.8060806@sentex.net> <550C5AAF.9060502@sentex.net> <550C8AEE.4090408@sentex.net> <550CB306.7030405@delphij.net> <20150321001559.GB2379@kib.kiev.ua> In-Reply-To: <20150321001559.GB2379@kib.kiev.ua> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: John-Mark Gurney , FreeBSD-STABLE Mailing List , John Baldwin X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 21 Mar 2015 00:28:16 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 03/20/15 17:15, Konstantin Belousov wrote: >> For the purpose of devfs, does it make sense to bump timestamps >> like normal filesystems for each read/write operation? Looks >> like Mac OS X will bump timestamps for each operation but Debian >> don't. > > First question is, what timecounter hardware is used. I would > accept some slowdown from hardware like HPET, but it is indeed > surprising if caused by TSC. It was HPET (see earlier discussion where a FlameGraph is posted). I've done a survey on a few other operating systems, including OpenIndiana, Debian and OS X. Neither OpenIndiana nor Debian update timestamp for read/write events so I'd propose this change to make it a runtime configurable behavior and disable by default: https://reviews.freebsd.org/D2104 Cheers, - -- Xin LI https://www.delphij.net/ FreeBSD - The Power to Serve! Live free or die -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.1.2 (FreeBSD) iQIcBAEBCgAGBQJVDLscAAoJEJW2GBstM+nsGtMQAKyh3kW6VWPnCd353KELqeoE 3n295iHqVjAF6vszt71cfiAqlz0oSH+5i2SfR1LKVXH4cb2gMbXYbMeJVQiV7L93 8xEsBNtPF4Z/fxwyEBfFb3WcXHo+TGjvaCEbsuJIFKhqa4GPY230/7JELN/LXuNd HJlP7YECNPgeVWyYuCdZkLu/BMOPjL44/wcC/YuXSQP65TK54kx59KLg671o9Z2R ffpljAmJSqpNjas41qyVN+SNxr9ga8oQA0LTf8lbn3r4o2mx+te8yzNcyIn/gCU8 jawDGfGNiEvCTr76ST6rvELy4jFbmZyNFrbu+TA6VDT2/CCh1x5qhDceXTnZKPtX iJFpDKsl87R5aXdRQjwCZKkTdaJ7AuRAG0lrmumxIlblgDmaDsVbmaqR1CU0JzWI rvGblL6iwm/4pL+O9Igkr6oN6+yd1/9KM2yCB5BZDokLnoj6INWOft4z6jGyOUWh T3oNVfB48g/j5NKRyU/vFvJIUix2mbE5ziem+RyLU6x/UOdYQJsKRIlN6xPiIx73 /G7kpT1JbsoS47fyere5jeUV2UOurRuH5UfBHjJCJ0X44tzrsMhTm3Vs2cOzJP7K 6SNbyxyCbX3uJN1Aq9nhg2scIVieV1/BRLoeI6LEVVZKTTig4LA8ekzb0P6e1Fwg f9rvXNwpdeZPmsDwdpff =Uxnt -----END PGP SIGNATURE-----