From owner-freebsd-hackers Fri Feb 1 13:48:27 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mailsrv.otenet.gr (mailsrv.otenet.gr [195.170.0.5]) by hub.freebsd.org (Postfix) with ESMTP id DAE7337B402 for ; Fri, 1 Feb 2002 13:48:20 -0800 (PST) Received: from hades.hell.gr (patr530-a060.otenet.gr [212.205.215.60]) by mailsrv.otenet.gr (8.12.2/8.12.2) with ESMTP id g11Lm5LA003829; Fri, 1 Feb 2002 23:48:06 +0200 (EET) Received: (from charon@localhost) by hades.hell.gr (8.11.6/8.11.6) id g11LZvu06601; Fri, 1 Feb 2002 23:35:57 +0200 (EET) (envelope-from keramida@freebsd.org) Date: Fri, 1 Feb 2002 23:35:56 +0200 From: Giorgos Keramidas To: Storms of Perfection Cc: replicator@ngs.ru, hackers@freebsd.org Subject: Re: Clock Granularity (kernel option HZ) Message-ID: <20020201213556.GC5412@hades.hell.gr> References: <2651.208.141.46.249.1012504967.squirrel@test.outloud.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2651.208.141.46.249.1012504967.squirrel@test.outloud.org> User-Agent: Mutt/1.3.25i Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG I've been running for quite some time a 5.0-CURRENT box with HZ=1000 set to it's kernel configuration. Apart from a faster blinking rate of the syscons cursor, I haven't seen much difference. This is my own personal workstation though, and it's almost never loaded too much :-/ - Giorgos On 2002-01-31 14:22, Storms of Perfection wrote: > I am intrested in this as well. > > > I've seen various postings on the Net where people reported > > network-related and overall performance improvements caused > > by settig HZ kernel option to 1000 (for example), that is, > > reducing a tick size to 1ms for their FreeBSD and Linux > > systems. However, several problems seem to arise, such as > > some device drivers do not include HZ in calculating their > > timeout value, but simply assume HZ to be 100, and also some > > utility programs such as top or ps take timing information > > from the kernel in ticks, also assuming 10ms ticks, however, > > most of these saying were related to Linux. How safe it is > > to bump up HZ to, say, 1000 in FreeBSD (I use 4.5-STABLE)? > > What pitfals will I encounter (drivers, top/ps)? Is there > > are going to be [promised] performance increase? Do I > > really need it? Thank you. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message