Article: Parallelism at HotPar 2010
By: Richard Cownie (tich.delete@this.pobox.com), August 4, 2010 3:24 pm
Room: Moderated Discussions
Gabriele Svelto (gabriele.svelto@gmail.com) on 8/4/10 wrote:
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>That's debatable, Nehalem doesn't seem to offer much improvement in per-core performance
>over Core 2 (in my experience at least)
I daresay there are particular examples for which that
is true. But my own experience with a big app is
completely the opposite: just a couple of weeks ago
I ran the exact same executable on a Core2 Xeon 2.93GHz
and a Nehalem Xeon 2.93GHz, and got 1.51x speedup.
And these are still 45nm parts without the TurboBoost
trick.
That's a pure single-threaded app, so there's no benefit
from the hyperthreading.
It seems like a really big win. And I get the impression
that most people see Nehalem that way.
You're welcome to have your opinion, based on your own
experience. But I don't think it matches what most
people have measured.
---------------------------
>That's debatable, Nehalem doesn't seem to offer much improvement in per-core performance
>over Core 2 (in my experience at least)
I daresay there are particular examples for which that
is true. But my own experience with a big app is
completely the opposite: just a couple of weeks ago
I ran the exact same executable on a Core2 Xeon 2.93GHz
and a Nehalem Xeon 2.93GHz, and got 1.51x speedup.
And these are still 45nm parts without the TurboBoost
trick.
That's a pure single-threaded app, so there's no benefit
from the hyperthreading.
It seems like a really big win. And I get the impression
that most people see Nehalem that way.
You're welcome to have your opinion, based on your own
experience. But I don't think it matches what most
people have measured.