On Mar 26, 2013, at 6:44 AM, Bob Friesenhahn <[email protected]>
wrote:
> On Tue, 26 Mar 2013, Sašo Kiselkov wrote:
>>
>> Once I gave it bit more thought, I realized tmpfs *should* be faster,
>> since it doesn't traverse the block device/SCSI interface and instead
>> intercepts calls pretty high up the VFS stack. Nonetheless, I suspect
>> the tmpfs implementation isn't really designed for multi-GB/s throughput
>> (it's a filesystem for /tmp FFS, it's supposed to hold a couple of kB of
>> data anyway).
>
> Sašo, you are continuing to ignore that the simple dd to tmpfs test turned in
> abysmal results on this quad Xeon E5 system as compared to the many other
> systems tested.
>
> This seems to be a problem with the system, or the way Illumos runs on it.
Not necessarily. Higher lock contention can lead to surprising results in some
configurations. (Such as the speed of certain benchmarks actually *improving*
by either offlining cores or reducing processor speeds.) Whether that's the
case here I don't know. But tmpfs is the *wrong* way to benchmark memory speed.
I do have illumos on a Xeon E5 in my garage. It works pretty well, but I've
not spent a lot of time benchmarking or testing memory bandwidth.
- Garrett
>
> I had not heard of Illumos running on a quad Xeon E5 system before now. It
> is doubtful that Illumos has been seriously tweaked/tuned for particular
> newer hardware since the days of Sun. Most efforts seem on the level of
> keeping things running properly without the considerable resources required
> for performance tuning/testing. Maybe there are significant issues to be
> resolved.
>
> Bob
> --
> Bob Friesenhahn
> [email protected], http://www.simplesystems.org/users/bfriesen/
> GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
>
>
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