[Twisted-Python] Twisted server is 5 times SLOWER on Solaris than Linux?

Jean-Paul Calderone exarkun at divmod.com
Wed Jan 17 15:37:19 MST 2007

On Wed, 17 Jan 2007 17:18:13 -0500, Jarrod Roberson <jarrod at vertigrated.com> wrote:
>I we have a basic twisted server that we have doing nothing but dropping
>received bits on the floor, and sending back a static response.
>We have tested it on a Solaris 10 on a Sun T1000 ( 8 cores ) and on Solaris
>8 on a Sun V210.
>We did initial load testing on a Dell 2850 ( 2 Hyperthreaded P4's ) using
>Red Hat WS 3 (Taroon Update 4) / (  Linux 2.4.21-27.ELsmp )
>The Solaris boxes are all showing latency 5 times what we are seeing on the
>Dell 2850 with 1/5 as many clients to boot.
>On the Dell 2850 ( linux thinks it is a quad processor box ) our Twisted
>server is more Network I/O bound than CPU bound until we get to around 800 -
>900 clients, latency is manageable all the way up to about 1400 clients, at
>which time they start getting progressively worse.
>All the Sparc boxes start out CPU bound at about 200 clients and latencies
>are way worse than Linux with 1400 clients.
>The only Solaris 10 x86 box we have to test on is so old it is almost
>impossible to compare to even the Dell 2850. :-(
>We are using Python 2.4.4 and Twisted 2.4.0 using the poll reactor in all
>Anyone have any idea why we are seeing such poor performance on Solaris?
>Is it the Sparc hardware?

I don't have any specific experience with Twisted on Sparc hardware, but
one thing I'll point out is that Twisted is single threaded.  Whether there
are 4 cores or 8 probably won't make any noticable difference to a Twisted
application's performance.

It looks like a single core on a T1000 is much less powerful than a single
core in a Dell 2850, so this might account for some of the difference.


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