question about Intel P4 versus Alpha's

Dominic Wu dwu at
Fri Jan 10 09:53:21 PST 2003

Is HT anything more than a thinly-veiled attempt at luring more software
developers to develop multi-threaded applications so as to help Intel sell
more CPU in the future?  (I.E. the new fangled software that is optimized
for HT can really benefit from additional REAL processors instead of using
just HT?)

 -----Original Message-----
From: 	beowulf-admin at [mailto:beowulf-admin at]  On
Behalf Of Nathan Fredrickson
Sent:	Friday, January 10, 2003 9:15 AM
To:	Daniel Kidger
Cc:	beowulf at
Subject:	RE: question about Intel P4 versus Alpha's

Daniel Kidger wrote:
> In general, people prefer to switch off hyperthreading for HPC clusters,
> either via a BIOS option, or by passing 'noht' to the kernel (in say
> grub.conf).

Why is HT off preferred for HPC clusters?  I know it is beneficial to
disable HT until you upgrade to a kernel that has an HT aware scheduler
(either a patch to 2.4.19 or the upcoming O1 scheduler in 2.5).  Is that the
reason here, or is there another reason to not use HT in a HPC cluster?


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