From owner-freebsd-hackers@FreeBSD.ORG Tue Sep 16 23:17:22 2014 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 00925597; Tue, 16 Sep 2014 23:17:21 +0000 (UTC) Received: from mail-qg0-x235.google.com (mail-qg0-x235.google.com [IPv6:2607:f8b0:400d:c04::235]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 77A6ABA8; Tue, 16 Sep 2014 23:17:21 +0000 (UTC) Received: by mail-qg0-f53.google.com with SMTP id q108so834915qgd.12 for ; Tue, 16 Sep 2014 16:17:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=4l5R6ojs/BoDKkIkv8NRpj9l6nMGrIBi9Ru5NUprgwI=; b=LfuhtDdGXn+s7cObqewgyiC3ERHdGdbcIACX2OAYAHkK1e9BEFXI4Og/IwnEBwUZ3z KfzaVbvkZme8y+VgLYzJTkVlx/lnJdEXCjP25xRf1CN0s+Sikol5+6fe0fJMtLEtVBut A95OSQvFol41dF8+ctGEk0DWluExsDEJRaouz1ur7N3ZZTBYygPVwCm0nxI2Cq46KYrg 93OmVHUpFBqweZo/R+w95lxBq2et2qjPYh4F2HSWJ/HvwbNpBNIyW9KosC/9tK1agsKd t5iTtgYN3m/cnazoQoQvatqBWVyJlvYrirDo7LTQaVxa4aW+My+Ur8WX7TmzspfA4wSP 5wPw== MIME-Version: 1.0 X-Received: by 10.229.249.8 with SMTP id mi8mr28280524qcb.6.1410909440657; Tue, 16 Sep 2014 16:17:20 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.224.39.139 with HTTP; Tue, 16 Sep 2014 16:17:20 -0700 (PDT) In-Reply-To: <52A731FD.8060307@FreeBSD.org> References: <5295A261.2060403@FreeBSD.org> <529F4409.9080403@FreeBSD.org> <52A1B869.6080407@FreeBSD.org> <52A21AE9.5020803@FreeBSD.org> <52A731FD.8060307@FreeBSD.org> Date: Tue, 16 Sep 2014 16:17:20 -0700 X-Google-Sender-Auth: 08wbhFiKGMktHGHguZyfb9maQDs Message-ID: Subject: Re: 9.1 callout behavior From: Adrian Chadd To: Alexander Motin Content-Type: text/plain; charset=UTF-8 Cc: Bret Ketchum , "freebsd-hackers@freebsd.org" X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 Sep 2014 23:17:22 -0000 Hi! I know this is bringing up an old thread, but Dell has shipped us some hardware (thanks Dell!) and I'm helping them take a look at it. On 10 December 2013 07:23, Alexander Motin wrote: > On 10.12.2013 17:12, Bret Ketchum wrote: >> >> Do either of you have a dual socket/package motherboard to play >> with? I've tried a couple single socket motherboards and cannot >> reproduce the issue. I'm wondering if this occurs on only multi-socket >> mobos. > > > My main test system is dual-socket (Supermicro X8DTU). It's reasonably reproducable. The tscdrift tool from jhb (in tools/tools/tscdrift) looks thus: root@appollyon:~/src/tscdrift # ./tscdrift CPU | TSC skew (min/avg/max/stddev) ----+------------------------------ 0 | 0 0 0 0.000 1 | 34 79 380 39.005 2 | 306 476 1326 120.472 3 | 306 485 1426 123.487 4 | 280 473 7500 248.965 5 | 280 462 1320 126.691 6 | 300 461 1934 129.362 7 | 300 470 1354 122.654 8 | 292 420 3640 152.029 9 | 135 190 655 58.601 10 | 112 188 620 56.490 11 | 114 189 660 62.440 12 | 129 204 566 53.731 13 | 129 206 617 56.047 14 | 126 211 620 54.450 15 | 126 213 603 54.808 16 | 440 590 1683 217.649 17 | 440 612 1606 234.295 18 | 468 642 4017 266.768 19 | 463 653 8683 352.624 20 | 480 671 1500 255.395 21 | 480 689 8060 348.384 22 | 468 707 3766 296.721 23 | 466 703 1683 284.625 24 | 480 767 8183 373.741 25 | 486 782 7400 362.069 26 | 480 664 1620 249.125 27 | 477 686 3669 278.144 28 | 469 621 1897 226.673 29 | 469 649 8275 363.575 30 | 457 636 1835 250.005 31 | 451 641 4300 272.322 If I modify their supplied ticktock module to call callout_reset_on(args, 0); to call on CPU #0, then it actually doesn't seem to drift. I'm going to look at mav's recent patch to the scheduler in case it has an effect on things. -a