From owner-freebsd-hackers@FreeBSD.ORG Fri Dec 4 21:10:21 2009 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D02BC1065679; Fri, 4 Dec 2009 21:10:21 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: from ey-out-2122.google.com (ey-out-2122.google.com [74.125.78.25]) by mx1.freebsd.org (Postfix) with ESMTP id 31B3B8FC12; Fri, 4 Dec 2009 21:10:20 +0000 (UTC) Received: by ey-out-2122.google.com with SMTP id 22so682263eye.9 for ; Fri, 04 Dec 2009 13:10:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:from:date:x-google-sender-auth:message-id:subject:to:cc :content-type:content-transfer-encoding; bh=qpYxy5QgU3o/HV7IpByDQVwxIWysZ0hcvAx4pctkBvM=; b=Jr6ZCb+Zj4xs/4lpNj1xs6stgA0bYAZNoHRk0mebBLLaJyuq2Jb5NKWvG0kcQuL3By alh2vcaLpjmUsXuBi5z5LWXC0HuiTGcNt9apKPFf5B939UvbdWIeg4zYE1ohTV+OH82p h3dwgQXrHFPAlYB+cLZ602h4rkbllZngdi0S8= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; b=LOJzStNEw0H8GarCvWFAWyllzte47YXnjy87UgN+B0DDwjLifKX+QQYB6sP4WJwL3R 2SziX1am1Gi96MuFfoS9o87op9upVDd7Mp7iP/dR0AvSTOuEMvilF186JwEg33uSss95 rHF9Zpay0qUxWLAP7qtEMw2YidB3BDOm6am9A= MIME-Version: 1.0 Sender: ivoras@gmail.com Received: by 10.216.88.71 with SMTP id z49mr1178585wee.90.1259961019218; Fri, 04 Dec 2009 13:10:19 -0800 (PST) In-Reply-To: <200912041047.08253.jhb@freebsd.org> References: <200912041047.08253.jhb@freebsd.org> From: Ivan Voras Date: Fri, 4 Dec 2009 22:09:59 +0100 X-Google-Sender-Auth: 3cde40eb5885c374 Message-ID: <9bbcef730912041309m51ce4858q42937e0f76f94cda@mail.gmail.com> To: John Baldwin Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: freebsd-hackers@freebsd.org Subject: Re: Request for information - timers, hz, interrupts X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Dec 2009 21:10:21 -0000 2009/12/4 John Baldwin : > On Friday 04 December 2009 9:52:39 am Ivan Voras wrote: >> For a long time, at least in the 6-stable timeframe, I was used to >> seeing timer interrupts going at the frequency of 2*HZ, e.g. this is >> from 6.4-RELEASE: >> >> kern.clockrate: { hz =3D 250, tick =3D 4000, profhz =3D 1000, stathz =3D= 142 } >> kern.hz: 250 > It actually was changed to provide saner behavior when you use low hz val= ues > like 'hz=3D100'. =C2=A0Note that your stathz is now 142 instead of 33. = =C2=A0The scheduler > is likely far happier with that stathz. =C2=A0There is more detail in the= commit > log I believe (just look at the logs for local_apic.c in either svn or > cvsweb). Ok. Some more questions: What does "ticks" do in the above sysctl output? So 4000 interrupts/s per CPU in the default configuration isn't considered excessive? :) I see stathz isn't a divisor of any number in kern.clockrate, which probably means it's not triggered from one of them firing; can't it be a separately configurable value?