From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <737a0ebd8ffbbd4d878cadf0d978763c@plan9.bell-labs.com> From: jmk@plan9.bell-labs.com To: 9fans@cse.psu.edu Subject: Re: [9fans] hyperthreading In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Sat, 27 Dec 2003 13:39:56 -0500 Topicbox-Message-UUID: b01fa6fa-eacc-11e9-9e20-41e7f4b1d025 I took a quick look at the P4 hyperthreading docs. It looks like we'd have to use the ACPI tables rather than the BIOS MPS table to correctly initialise the extra logical CPUs if the MPS table doesn't lie and pretend the logical CPUs are physical ones. That's more work than anyone here has time for right now. Some ACPI support would be nice in general, though. On Fri Dec 26 19:01:39 EST 2003, jmk@plan9.bell-labs.com wrote: > On Fri Dec 26 18:06:45 EST 2003, mirtchov@cpsc.ucalgary.ca wrote: > > quick question: > > > > will Plan 9 work with hyperthreading processors? will it recognize them as > > dual-cpus? > > > > can you share experience with those? > > > > thanks: andrey > > Depends. In 2002 we bought a dual-processor Xeon machine with > hyperthreading. After enabling the hyperthreading option in the > BIOS setup Plan 9 detects and uses 4 processors. (I don't think > it makes much, if any, improvement to the system's performance). > > Earlier this month we tried a new single-processor P4 system > with hyperthreading. Even with the BIOS option set the BIOS MP > table only contains a single processor entry. I haven't bothered > yet to look to see if there's some BIOS problem or if there's > some other way to take advantage of hyperthreading on this > system.