Re: [Xen-devel] Hyperthreading network benchmark

[Kip Macy <kmacy@xxxxxxxxxxxxxxx>]

They've seen anywhere from a 30% decrease to 30% increase in performance
on SPECint with hyperthreading turned on. Bear in mind you're now
sharing a single cache between two processes. For many workloads the
trace cache on the P4 was too small to begin with.

                                -Kip


On Sat, 30 Oct 2004, kuas wrote:

> Hi all,
>
> I found enabling hyperthreading for Xen (the hypervisor layer) would
> degrade network performance. I wonder if the synchronization cost of Xen
> (the hypervisor) running on multi cores/multiprocessors environment is
> high (around 30 %). The benchmark I did is against Intel Pentium 2.4 MHz
> Hyperthreaded CPU and Gigabit network (ethernet and switch). I was using
> WebStone 2.5 benchmark against Apache 2.0.50-1.0 (FC1 httpd package).  I
> was also running 2.4.27 for the domains kernel. The result I have:
> 1. Native:
>     a. Hyperthread enabled: 370 Mb/sec
>     b. Hyperthread disabled: 270-290 Mb/sec
> 2. Domain 0 has the same performance around: 270 Mb/sec
> 3. Domain 1:
>     a, Hyperthreaded enabled, domain1 run on different core: 175-185 Mb/sec
>     b. Hyperthreaded disabled or even if enabled domain 1 is forced to
> be in the same Core with domain 0: 255-265 Mb/sec
>
> Please note, I was only sending request to one domain at a time. It
> seems when the two domain ran in the same core we had higher
> performance. I wonder if any other people has done almost similar test
> and have similiar/opposite behavior. Are these behaviors make sense?
>
> Thanks in advance for any comments.
>
> Kuas.
>
>
>
>
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