Date: Thu, 14 Aug 2003 09:59:58 -0600 From: "David R. Colyer" <davedillinger@wyoming.com> To: freebsd-current@freebsd.org Subject: Re: Dual P4 2.4Ghz Xeon With Hyperthreading enabled... Message-ID: <200308140959.58487.davedillinger@wyoming.com> In-Reply-To: <XFMail.20030813125214.jhb@FreeBSD.org> References: <XFMail.20030813125214.jhb@FreeBSD.org>
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No doubt this has been answered before, but I have an asus p4pe with a 3.06 p4. Naturally, it is enabled in the bios. To enable hyperthreading do I need to recompile my kernel with smp support, and if so...does this apply to freebsd 5.1 release as well? (my friend wants to know). Additionally does changing the machdep.cpu_idle_hlt to zero make it faster? Thanks in advance. David R. Colyer On Wednesday 13 August 2003 10:52 am, John Baldwin wrote: > On 13-Aug-2003 Dr. Richard E. Hawkins wrote: > > On Wed, Aug 13, 2003 at 11:35:14AM -0400, John Baldwin wrote: > >> On 13-Aug-2003 Dr. Richard E. Hawkins wrote: > >> > On Tue, Aug 12, 2003 at 08:33:57PM -0500, Cagle, John (ISS-Houston) wrote: > >> >> I think the valid settings are only 0 or 1, with the default being 1 > >> >> which will disable all logical CPUs. If you want to enable the extra > >> >> logical CPUS, then set it to 0 (zero). They will come online > >> >> immediately. > >> > > >> > That can't be right. I've never done anything to configure the > >> > logical cpus on mine; they just showed up unexpectedly when i switched > >> > from stable to current. Now I have: > >> > > >> > slytherin ttyp1:hawk>sysctl -a | grep cpu > >> > kern.threads.virtual_cpu: 4 > >> > kern.ccpu: 1948 > >> > kern.smp.cpus: 4 > >> > hw.ncpu: 4 > >> > machdep.cpu_idle_hlt: 1 > >> > machdep.hlt_cpus: 10 > >> > machdep.hlt_logical_cpus: 1 > >> > machdep.logical_cpus_mask: 10 > >> > > >> > It launches four logical cpus all on it's own. It did panic during > >> > shutdown yesterday; If I read the messages right as it flashed by, it > >> > was because cpu#2 got the shutdown order. > >> > >> Your logical CPU's aren't doing anything though, even though they are > >> started up. John's explanation is correct. > > > > I've also got the report in dmesg, > > > > SMP: AP CPU #1 Launched! > > SMP: AP CPU #2 Launched! > > SMP: AP CPU #3 Launched! > > > > > > Doesn't this mean that they *are* active? > > No, it means the kernel has started them up. CPU's whose bits are set > in machdep.hlt_cpus don't execute any user tasks. Instead, they just > sit in a loop executing the 'hlt' instruction doing nothing but servicing > interrupts.
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