Date: Thu, 12 Apr 2007 15:40:48 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: Dag-Erling =?iso-8859-1?Q?Sm=F8rgrav?= <des@des.no> Cc: Randall Stewart <rrs@cisco.com>, freebsd-current@freebsd.org, Ivan Voras <ivoras@fer.hr>, Brad Penoff <penoff@cs.ubc.ca>, Janardhan Iyengar <iyengar@conncoll.edu> Subject: Re: CPU utilization Message-ID: <20070412153930.A99718@fledge.watson.org> In-Reply-To: <86d529zxci.fsf@dwp.des.no> References: <461E0078.3050001@cisco.com> <evl00c$89j$1@sea.gmane.org> <461E092B.4080001@cisco.com> <86d529zxci.fsf@dwp.des.no>
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This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --0-1967887432-1176388848=:99718 Content-Type: TEXT/PLAIN; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE On Thu, 12 Apr 2007, Dag-Erling Sm=F8rgrav wrote: > Randall Stewart <rrs@cisco.com> writes: >> machdep.hyperthreading_allowed: 0 > > Note that enabling hyperthreading is more likely to harm performance than= to=20 > help it. You should just disable it in the BIOS, and run a UP kernel. Historically this has been true, but some more recent results I've seen=20 suggest that both hyperthreading hardware has improved, and the efficiency = of=20 our SMP implementation and scheduler has lead to it being more effective us= ed.=20 I would reevaluate this on more modern hardware and using a more recent ker= nel=20 before assuming this remains true for your application. Robert N M Watson Computer Laboratory University of Cambridge --0-1967887432-1176388848=:99718--
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