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From Cliff Woolley <jwool...@virginia.edu>
Subject Re: Strange Behavior of Apache 2.0.43 on SPARC MP system
Date Wed, 12 Feb 2003 05:30:28 GMT
On Tue, 11 Feb 2003, Min Xu wrote:

> I don't understand, if the client is blocked, it only be woke up when
> the server reply is avaiable. In that case, the server should have done
> it is job. In other words, the client is not spinning, it is instead
> put on sleep when calling read syscall.

Of course the client isn't spinning, but your statement that "the server
should have done its job" assumes that the entire response is sent at
once.  Depending on its length, it is entirely possible that the server
would send the response in multiple packets.  But as soon as *any* packets
arrive, the client is woken up.  That means that the server and the client
are vying for timeslices.  Let's say the client gets it.  The client
receives the partial response and then goes right back to sleep again.
Sure the server wakes right back up and starts sending more of the
response, but in the meanwhile, several context switches had to happen.

--Cliff


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