Debian hyperthreading support
Nathen
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. :)
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Angus Hedger
Nathen <n1472...@googlemail.com> 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. :)
>
>
Linux has handled hyperthreading since 2.4.x.
As for performance, see here [1] in general it doesn’t hurt performance,
but doesn’t help much either.
[1] http://java-monitor.com/forum/showthread.php?t=552
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Angus Hedger
Debian GNU/Linux User PGP Public Key 0xEE6A4B97
Angus Hedger
Nathen <n1472...@googlemail.com> 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. :)
>
>
Sorry, the link was bad (for p4 hyperthreading) its late, my bad.
Reading more, it seems that with the atom, hyperthreading really helps
with parallel tasks, so I would leave it on.
I cant find any benchmarks of it on vs it off, and I dont have a spare
HDD to boot the atom330 I have to do some of my own.
Nathen
it's not very CPU-intensive, I wanted to be sure I wasn't wasting
performance by having it enabled, for example.
Thanks
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Mark Allums
> 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, but I think Debian
and Atoms are good.
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Camaleón
> Thanks for replying. The system is running mainly a file server so it's
> not very CPU-intensive, I wanted to be sure I wasn't wasting performance
> by having it enabled, for example. Thanks
I don't think you are going to get any penalty in performance by using a
kernel with HT enabled (in fact, that could have happened for some P4
featuring the "replay system" but I fairly doubt it is still live in Atom
based CPUs) :-?
Greetings,
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Camaleón
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Arnt Karlsen
<4CA7DF69...@allums.com>:
> 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.
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..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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