On Sunday 03 September 2006 8:55 pm, Nathan Allen Stratton wrote:
> Chip Clock HT Cache Bus Speed
> ---------------------------------------------------------
> 5080 3.7 GHz YES 2MB 1066 MHz
> 5160 3.0 GHz NO 4MB 1333 MHz
>
> Does the .7 GHz and HT worth more then 4MB cache and higher bus speed? The
> application is VoIP so there is not a lot of IO so I would not think Bus
> Speed would matter. I am finding mixed information on HT, some say it is
> great, others say it actually slows things down, could this be why the new
> chips done have HT?
HT helps to avoid context switches when used with an HT-aware scheduler. it
can be very significant for I/O in Xen because everything a DomU does has to
pass through Dom0 for I/O. dedicating an HT thread exclusively for Dom0 is
almost as good as giving it a full real core, but usually much cheaper.
AFAIK, all Xen schedulers, all modern Linux, BSD and Solaris kernels are fully
HT-aware, and make good use of it. I also think (but not sure) that some
servicepacks for win2k and winXP gave them most, if not all, of the
advantages of a modern scheduler.
the only remaining cases where HT impacts negatively are heavy single threaded
tasks. there, you'd like to dedicate the whole processor to a process during
its timeslice, without other tasks taking up resources (cache, rename
registers, FSB, etc)
with server-like workloads, even more with Xen, HT is usually a good thing.
i have no clue why newer chips doesn't have it, neither why AMD never bothered
with something like that. maybe there's some other consideration i don't
know about.
--
Javier
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