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From Min Xu <>
Subject Re: Strange Behavior of Apache 2.0.43 on SPARC MP system
Date Wed, 12 Feb 2003 01:05:15 GMT
On Tue, Feb 11, 2003 at 03:11:36PM -0800, David Burry wrote:
> Because the client will contend very heavily with the server for many
> system resources.  It's indeterminate which one (client or server)
> requires more resources, which one wins more, and how much more of which
> resources.

Well, I am not defending this server/client-on-one-system is better
or anything. Just want to understand this better. Isn't the clients
block when the servers can not response? From a higher level of point
of view, the system is a closed queuing system. In the steady state
there should be a balance between servers and clients, right?

> Running both on the same machine will certainly stress the
> machine pretty well, but you can't compare any measurement you get with
> what the same machine will perform if Apache doesn't have to contend
> with a client for its resources, it won't be the same result at all.

We have no intention to compare these two at all. Our goal was to
achieve a reasonable workload that runs similarly as the real world

> In
> the real world apache doesn't have a client stealing its system
> resources, therefore an accurate test of how apache would behave in the
> real world can only be done if you set up a test with the same
> situation.  This could be why apache is performing better when you let
> your client sleep a little (then again, it could be something else,
> that's why I say it's "indeterminate" (unknown) how much of the
> resources the client itself is stealing away from the server).  To
> measure the effect of anything, you have to limit the number of
> variables that can influence the result.

I agree. We indeed tried other experiments to test this hypothesis.
We first used separate machines for the clients and this behavior
disappeared. But I think the reason was the network(ethernet) latency
between those server and client machines enssentially served as the
small delay time I have added in the singal machine case. On the other
hand, I have used solaris "psrset" to logically divide the 14p server
into "two" machines, and I bind the server and the client to different
processor sets. And the results shows again the small delay time have
important impact on system throughput.

How strange!

Rapid keystrokes and painless deletions often leave a writer satisfied with
work that is merely competent.
  -- "Writing Well" Donald Hall and Sven Birkerts

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