Date: Fri, 31 Jan 2003 10:24:58 -0800 (PST) From: Nate Lawson <nate@root.org> To: John Baldwin <jhb@FreeBSD.org> Cc: cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: RE: cvs commit: src/sys/i386/i386 mp_machdep.c Message-ID: <Pine.BSF.4.21.0301311023040.96929-100000@root.org> In-Reply-To: <XFMail.20030131121010.jhb@FreeBSD.org>
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On Fri, 31 Jan 2003, John Baldwin wrote: > On 30-Jan-2003 Matthew Dillon wrote: > > Ouch. That's rather counter-intuitive since idle_hlt usually > > degrades performance, but I see how it would improve performance on > > an HTT box. > > Well, idle_hlt can only really hurt if you are doing compute bound stuff. > You get at least 128 clock interrupts per second from the RTC that get > IPI'd to all the other CPUs, so no CPU would errantly stay halted for more > than 1/128th of a second with idle_hlt on anyways. As Peter has mentioned, > the idle_hlt thing shows some rather impressive thermal benefits, and I > imagine it can provide power savings of some sort. I would argue that > being fully compute bound is not the common case and that we should probably > default to having it on in general. Why not check CPU utilization and dynamically en/disable HLT? -Nate To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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