On Wed, Oct 12, 2005 at 04:05:40PM -0400, michael chang wrote: > On 10/12/05, Woods, Jeff <[EMAIL PROTECTED]> wrote: > > > > Is it possible to explicitly specify a value for the static metrics such as > > cpu_num? > > > > We have a number of nodes in our cluster which have hyperthreading enabled, > > where each physical CPU appears as two CPUs to the OS. Our applications are > > not threaded, so we get little or no benefit from having the hyperthreading > > enabled (yes, we could disable it in the BIOS, but I would like to leave it > > enabled "just in case"). Further, we have CPUs (in our head or I/O nodes, > > IIRC, for single-threaded CPU intensive operations, hyperthreading > actually decreases throughput, so it may be an idea to turn it off.
Depends on the OS and the application. Recent benchmarks in FreeBSD 6.0 seem to show it's a wash for SMP systems unless the applications cause a lot of pipeline stalls (most FPU heavy apps do this) in which case it a win. UP systems running one, single threaded application may see reduced perfomrance, if nothing else from the overhead of atomic operaions. If you're already using SMP you have to eat that cost anyway. -- Brooks -- Any statement of the form "X is the one, true Y" is FALSE. PGP fingerprint 655D 519C 26A7 82E7 2529 9BF0 5D8E 8BE9 F238 1AD4
pgpRIWCrhgi0x.pgp
Description: PGP signature
