Date: Wed, 13 Aug 2003 12:52:14 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: "Dr. Richard E. Hawkins" <hawk@slytherin.ds.psu.edu> Cc: current@FreeBSD.org Subject: Re: Dual P4 2.4Ghz Xeon With Hyperthreading enabled... Message-ID: <XFMail.20030813125214.jhb@FreeBSD.org> In-Reply-To: <20030813162033.GD6964@slytherin.ds.psu.edu>
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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. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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