Re: Debian hyperthreading support

On Sat, 02 Oct 2010 20:42:01 -0500, Mark wrote in message
<4CA7DF69.7040306@xxxxxxxxxx>:

On 10/2/2010 6:08 PM, Nathen wrote:
Pretty simple question really, does Debian i.e. the current Linux
Kernel handle hyperthreading well? I have a server running on an
Intel Atom D510, should I have HT enabled or disabled to get the
best performance?
Thanks. :)




Recently (kernel 2.6.31 or so) there has been a separate kernel
configuration option to optimize for SMT (Intel's word for it is
"hyperthreading"). Separate from SMP (multiple processor). Under
SMT, a single core running two threads looks like two cores to most
of the kernel itself and to user programs. This has been true for a
long time. Only now, there is more support and optimization for it.
If your kernel has it enabled, some workloads won't see any
difference, but some will benefit a lot. I think it is enabled by
default in the most recent stock kernels (please correct me if I'm
wrong.)

Note, you may need to enable hyperthreading in your BIOS, as well.

I would enable it for Core i7 and Atom. P4-era machines could
sometimes have software compatibility issues with it enabled,

..details, please, I'm trying to figure out what I did wrong in
my X|dri|etc setup on my FlightGear P4.

but I think Debian and Atoms are good.

--
..med vennlig hilsen = with Kind Regards from Arnt... ;o)
...with a number of polar bear hunters in his ancestry...
Scenarios always come in sets of three:
best case, worst case, and just in case.


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