From owner-freebsd-performance@FreeBSD.ORG Mon Jun 12 20:32:50 2006 Return-Path: X-Original-To: freebsd-performance@freebsd.org Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0722116A418; Mon, 12 Jun 2006 20:32:50 +0000 (UTC) (envelope-from kris@obsecurity.org) Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by mx1.FreeBSD.org (Postfix) with ESMTP id B518B43D46; Mon, 12 Jun 2006 20:32:49 +0000 (GMT) (envelope-from kris@obsecurity.org) Received: from obsecurity.dyndns.org (elvis.mu.org [192.203.228.196]) by elvis.mu.org (Postfix) with ESMTP id 99FFA1A4DA8; Mon, 12 Jun 2006 13:32:49 -0700 (PDT) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id 0321A5153E; Mon, 12 Jun 2006 16:32:48 -0400 (EDT) Date: Mon, 12 Jun 2006 16:32:48 -0400 From: Kris Kennaway To: Robert Watson Message-ID: <20060612203248.GA72885@xor.obsecurity.org> References: <20060612195754.72452.qmail@web33306.mail.mud.yahoo.com> <448DC818.9070100@samsco.org> <20060612210723.K26068@fledge.watson.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="mYCpIKhGyMATD0i+" Content-Disposition: inline In-Reply-To: <20060612210723.K26068@fledge.watson.org> User-Agent: Mutt/1.4.2.1i Cc: Scott Long , danial_thom@yahoo.com, freebsd-performance@freebsd.org Subject: Re: Initial 6.1 questions X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 Jun 2006 20:32:50 -0000 --mYCpIKhGyMATD0i+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jun 12, 2006 at 09:08:12PM +0100, Robert Watson wrote: > On Mon, 12 Jun 2006, Scott Long wrote: >=20 > >I run a number of high-load production systems that do a lot of network= =20 > >and filesystem activity, all with HZ set to 100. It has also been shown= =20 > >in the past that certain things in the network area where not fixed to= =20 > >deal with a high HZ value, so it's possible that it's even more=20 > >stable/reliable with an HZ value of 100. > > > >My personal opinion is that HZ should gop back down to 100 in 7-CURRENT= =20 > >immediately, and only be incremented back up when/if it's proven to be t= he=20 > >right thing to do. And, I say that as someone who (errantly) pushed for= =20 > >the increase to 1000 several years ago. >=20 > I think it's probably a good idea to do it sooner rather than later. It= =20 > may slightly negatively impact some services that rely on frequent timers= =20 > to do things like retransmit timing and the like. But I haven't done any= =20 > measurements. As you know, but for the benefit of the list, restoring HZ=3D100 is often an important performance tweak on SMP systems with many CPUs because of all the sched_lock activity from statclock/hardclock, which scales with HZ and NCPUS. Kris --mYCpIKhGyMATD0i+ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (FreeBSD) iD8DBQFEjc9wWry0BWjoQKURAoX7AKD3jrbSgbmpMEQibSGwucYvLxt9aACg3Y/i 5SbAlN+kIKUkkGdkZ3genJs= =+GDa -----END PGP SIGNATURE----- --mYCpIKhGyMATD0i+--