From owner-freebsd-hackers@FreeBSD.ORG Thu Feb 21 18:04:40 2013 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 9BE2C41E for ; Thu, 21 Feb 2013 18:04:40 +0000 (UTC) (envelope-from nonesuch@longcount.org) Received: from mail-we0-x234.google.com (we-in-x0234.1e100.net [IPv6:2a00:1450:400c:c03::234]) by mx1.freebsd.org (Postfix) with ESMTP id 3CC3FCD2 for ; Thu, 21 Feb 2013 18:04:40 +0000 (UTC) Received: by mail-we0-f180.google.com with SMTP id k14so7638991wer.39 for ; Thu, 21 Feb 2013 10:04:39 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:x-received:x-originating-ip:date:message-id:subject :from:to:content-type:x-gm-message-state; bh=jPHmJec2uLU7IHAAGwb3se68jQK7qGk/UIAc7sCnJvc=; b=In8tETLEon+rzqVDa5wRVAXIlCF4r6MnTxgllIWvYmFFAK7O/7NTySM9CCHStxu+x4 7yuZzkLlYWJgDYfxAB5+h4Hsri2ibxaqg1mghNddqnFKicGrz3ziLBK15xRdIPUmhei3 hcFVzttx7Me9ZbN418Y7n2slb6JFaRrSMUPe3TFBW/pXY+N7v6XeseMAUtsemOwRjieR kuwkGILDGOyCvxOByxXFalyPSmbm4iehpIpyRie1Qw5TxhjrB8Te7+++hOn5GpacYPrx U16nNT4yYFLBPzRuLAq7oG+lkroK//K4FuSBDKvqw97Rp2FJG9rCf1Jh10i+vuNIglqX 7x6w== MIME-Version: 1.0 X-Received: by 10.180.103.65 with SMTP id fu1mr24480066wib.4.1361469879343; Thu, 21 Feb 2013 10:04:39 -0800 (PST) Received: by 10.216.105.1 with HTTP; Thu, 21 Feb 2013 10:04:39 -0800 (PST) X-Originating-IP: [209.66.78.50] Date: Thu, 21 Feb 2013 13:04:39 -0500 Message-ID: Subject: Question on timecounter hardware / What cpu flag is constant_tsc From: Mark Saad To: "freebsd-hackers@freebsd.org" X-Gm-Message-State: ALoCoQmasV3lj0EcIc972xdrUmreRLdsVk/eX/Dns0t437MvOq68yatxZDZMFCk6oegypq8skMzX Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.14 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 21 Feb 2013 18:04:40 -0000 All I am looking into an issue with timecounter hardware on a number of HP DL165 G7's They all run FreeBSD 9.1-RELEASE and all have the same CPU and firmware. However they report strange results when you probe kern.timecounter.choice and kern.timecounter.hardware Take this example ssh root@ssr4 "sysctl kern.timecounter.choice" kern.timecounter.choice: TSC-low(-100) ACPI-safe(850) HPET(950) i8254(0) dummy(-1000000) ssh root@ssr4 "sysctl kern.timecounter.hardware" kern.timecounter.hardware: HPET dmidecode -s processor-version AMD Opteron(TM) Processor 6212 dmidecode -s processor-frequency 2600 MHz Unknown from dmesg.boot CPU: AMD Opteron(TM) Processor 6212 (2600.06-MHz K8-class CPU) Origin = "AuthenticAMD" Id = 0x600f12 Family = 15 Model = 1 Stepping = 2 Features=0x178bfbff Features2=0x1e98220b AMD Features=0x2e500800 AMD Features2=0x1c9bfff,> vs ssh root@ssr3 "sysctl kern.timecounter.choice" kern.timecounter.choice: TSC-low(1000) ACPI-safe(850) HPET(950) i8254(0) dummy(-1000000) ssh root@ssr3 "sysctl kern.timecounter.hardware" kern.timecounter.hardware: TSC-low dmidecode -s processor-version AMD Opteron(TM) Processor 6212 dmidecode -s processor-frequency 2600 MHz Unknown from dmesg.boot CPU: AMD Opteron(TM) Processor 6212 (2600.06-MHz K8-class CPU) Origin = "AuthenticAMD" Id = 0x600f12 Family = 15 Model = 1 Stepping = 2 Features=0x178bfbff Features2=0x1e98220b AMD Features=0x2e500800 AMD Features2=0x1c9bfff,> So my questions, what is the preferred time counter here ? In linux using TSC is preferred over hpet and to tell if you have a trusted TSC your cpu needs to support feature constant_tsc . Does anyone know what cpu feature this is; is it listed in my a fore mentioned dmesg.boot feature lists ? TIA -- mark saad | nonesuch@longcount.org