On Wednesday 09 June 2004 11:04 am, Dwayne MacKinnon wrote: > Hello, > > I'm in charge of upgrading a number of boxes from 4.8-RELEASE from > 4.10-RELEASE. My problem is this section of notes from the 4.9-RELEASE > errata: > > (28 Oct 2003) Very late in the release cycle, a change was made to the > HyperThreading (HTT) support on Intel® processors. HTT support is now > enabled by default on SMP-capable kernels; as a result, the HTT kernel > option is unnecessary and has been removed. The extra logical CPUs are > always started so that they can handle interrupts, but are prevented > from executing user processes by default. To enable the logical CPUs, > change the value of the machdep.hlt_logical_cpus sysctl(8) variable from > 1 to 0. This value can also be set from the loader as a tunable of the > same name. This behavior is now identical to FreeBSD 5.X. > > My boss is pretty adamant about not wanting the logical CPUs started at > all, let alone having them available for user processes. So, I'm > wondering if there's any straightforward way to disable them. Kernel > hacking is not a problem... we use custom kernels in our work anyway. > But I'd really appreciate a pointer in the right direction, as well as a > general idea of how difficult my life will get if I attempt this. > > (Note that I attempted to disable HT support in the BIOS. It didn't > have any effect. The logical CPUs still launched.)
The CPUs are not used to schedule any user processes. Unfortunately, if you completely turn them off the box will lock up due to the way interrupts are fielded in FreeBSD 4.x. If you really don't want to use them, you can turn off the use of TPR (there's some #define in a header, LOPRIO something I think), but it will send your performance into the toilet. -- John Baldwin <[EMAIL PROTECTED]> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
