On 03/18/2013 10:03 PM, Federico Lucifredi wrote:
On Mar 13, 2013, at 1:47 PM, [email protected] wrote:
The intel chips are 4 cores with four hyper-threads. Hyper-threads are
extremely limited pseudo cores, they are basically a parasitic add on a
single processing core that shares the instruction processor and
instruction cache. Unless the OS does a good job scheduling,
hyper-threading will reduce processing performance.
my assumption is that hyper-threading helps mitigate branch prediction
failures, if your app can feed twice the threads, that is.
I have some experience with hyper-threading both enhancing performance
and degrading performance. Our company's product is very CPU intensive
that uses things like montecarlo simulations does not do well with
hyperthreading, so we generally turn it off. but it also can help in a
non-cpu intensive situation. And, as Federico mentions, helps with
branch prediction.
--
Jerry Feldman <[email protected]>
Boston Linux and Unix
PGP key id:3BC1EB90
PGP Key fingerprint: 49E2 C52A FC5A A31F 8D66 C0AF 7CEA 30FC 3BC1 EB90
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