[AG-TECH] inquiry on the hardware specs...

[Justin Binns]

Our past experience with HyperThreading indicates that it does help under
Windows, but that the Linux scheduler is not hyper-threading friendly, and
it can actually *decrease* performance (that is, the scheduler in Linux
already does a pretty good job of keeping the processor(s) busy, having the
processors themselves double-scheduled doesn't help any, it just creates
contention for various critical memory regions).  We haven't really played
with it exhaustively for a while, though - more recent kernels (particularly
the 2.6 series) may be able to take better advantage of HT technology.

Justin

-----Original Message-----
From: owner-ag-tech at mcs.anl.gov [mailto:owner-ag-tech at mcs.anl.gov] On Behalf
Of Randy Groves
Sent: Wednesday, October 22, 2003 2:13 PM
To: ag-tech at mcs.anl.gov
Subject: Re: [AG-TECH] inquiry on the hardware specs...


The hyperthreading note below is intriguing - does it REALLY give us a 
boost by simulating two extra processors?  Any other experience here?

-randy

At 08:46 AM 10/21/2003, Harri Salminen wrote:

>I happened to notice that when the machine was temporarily in a single 
>processor mode (settable from BIOS) the AG lobby caused some problems 
>due to constant 100% CPU use but in dual processor (actually 
>hyperthreading shows it as 4 CPUs) mode it worked OK. The display vic 
>apparently is singlethreading and reserves only one processor up to 
>it's limit leaving enough CPU for all the rest including windows XP 
>pro, dppt, beacon, vnc and gentner AXP-800 control program.