Re: [Xen-users] Xeon 5160 vs 5080

[Nathan Allen Stratton <nathan@xxxxxxxxxxxx>]

On Sun, 3 Sep 2006, Javier Guerra wrote:

> 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)

All our applications run on Linux and all are threaded.

> with server-like workloads, even more with Xen, HT is usually a good thing.

So, would it make sense to go with the older 5080 and take the extra speed
and HT vs the newer 5160? The only unknown I have is on the CACHE, 2 MB vs
4 MB.


><>
Nathan Stratton                         CTO, VoilaIP Communications
nathan at robotics.net                  nathan at voilaip.com
http://www.robotics.net                 http://www.voilaip.com

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