Date: Mon, 15 Mar 2004 18:02:50 -0800 From: "Bharat Mediratta" <bharat@menalto.com> To: <freebsd-stable@freebsd.org> Subject: Re: HyperThreading CPU's Message-ID: <0d0d01c40afa$ccac1d30$c90c030a@bmedirattatg> References: <20040315152550.M213@Daath.hq.communityconnect.com> <20040315204827.GQ30555@therub.org>
next in thread | previous in thread | raw e-mail | index | archive | help
From: "Dan Rue" <drue@therub.org> ... > 20031022: > Support for HyperThread logical CPUs has now been enabled by > default. As a result, the HTT kernel option no longer exists. > Instead, the logical CPUs are always started so that they can > handle interrupts. However, the extra logical CPUs are prevented > from executing user processes by default. To enable the logical > CPUs, change the value of the machdep.hlt_logical_cpus from 1 to > 0. This value can also be set from the loader as a tunable of > the same name. Does 4.9 actually make effective use of HTT? I read recently (can't remember where, but I can probably find it if pressed) that in 4.8 enabling HTT was probably going to cause performance degradatation due to locking issues in the kernel. I've been itching to upgrade to 5.x to get more value out of my MP+HTT box, but don't want to upgrade until it's production release quality. If the 4.9 kernel really takes advantage of HTT, that would be worth upgrading for, IMO. -Bharat
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?0d0d01c40afa$ccac1d30$c90c030a>