Hi Min.

I'm not sure if this would make a difference in 2.0.43,
but you might want to configure apache to use non-portable-atomics
--enable-nonportable-atomics=yes

I think the worker MPM can then take advantage of this, and remove a mutex lock (replacing it with a spin) which may give you better performance with multiple CPUs.

1 other point.
you might want to disable some CPU's, and re-run your test. (eg.. on a 8 cpu machine) and see if that helps



Min Xu wrote:
Hi All,

Sorry I am posting this directly to the development list. But
I think this is not a user setup problem and it is so strange
maybe only you guys will have a clue on what's going on.

I am a student of UW-Madison. In order to study computer
architecture of commercial multiprocessor servers, we have used
APACHE as one of our important workloads.

I am the one who setup the workload on a 14-processor Sun
Enterprise server. During setup I found a very strange behavior
of the apache server (running with worker MPM). Essentially the
strange thing is that:

  The server optimal throughput is not achieved by using a
  greedy client, who drive the server with no think time. But
  with tiny amount of think time, much better throughput is
  archievable. Also, with the greedy client, the server's
  performance decreased over time, which seems to be very
  counter-intuitive.

Of course, just give you the short decription above does not
help you to help me. So I will give you the detail problem
description and data in the following. With the understanding
of the source code, maybe you can give me some more hypothesises
to try on.




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