Date: Thu, 12 Mar 2009 10:55:22 -0400 From: John Baldwin <jhb@freebsd.org> To: won.derick@yahoo.com Cc: robert@heron.pl, freebsd-smp@freebsd.org Subject: Re: only one logical CPU used in Xeon Message-ID: <200903121055.23408.jhb@freebsd.org> In-Reply-To: <418159.62247.qm@web45804.mail.sp1.yahoo.com> References: <418159.62247.qm@web45804.mail.sp1.yahoo.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thursday 12 March 2009 10:28:15 am won.derick@yahoo.com wrote: >=20 > --- On Thu, 3/12/09, John Baldwin <jhb@freebsd.org> wrote: > >=20 > > -----Inline Attachment Follows----- > >=20 > > On Wednesday 11 March 2009 11:01:51 > > am Oliver Fromme wrote: > > > Here's how you can see the details in the demsg > > output: > > > The older machine: > > >=20 > > >=A0 > Features =3D 0xbfebfbff <...,HTT,...> > > >=20 > > > The "HTT" bit in the features bitmask indicates that > > the > > > processor supports hyperthreading. > >=20 > > No, that flag just means it supports a register where you > > can ask for the=20 > > total number of threads/cores per package.=A0 Multi-core > > CPUs that don't have=20 > > hyperthreads have 'HTT' set, but when you read the > > registers properly you see=20 > > that they have 1 thread per core. > >=20 >=20 > Does this mean that the # of logical CPUs per core is not enough to=20 determine whether the machine supports hyperthreading or not? You've said=20 earlier that the newer machine is not hyperthreaded, so I'm assuming that=20 there is another part in the dmesg output that says so. more guidance pls. Your new machine might be hyperthreaded. I'm not really sure as it's a P4 descendant and I'm not sure if Intel released some dual-core P4 Xeon that had 2 threads per core. The current Core processors do not implement multi= ple=20 threads in their cores, but neither of your systems have those CPUs. =2D-=20 John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200903121055.23408.jhb>