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Date:      Tue, 25 Jan 2000 09:52:31 -0800 (PST)
From:      Matthew Dillon <dillon@apollo.backplane.com>
To:        "Scott Hess" <scott@avantgo.com>
Cc:        <freebsd-hackers@FreeBSD.ORG>
Subject:   Re: Performance issue with rfork() and single socketpairs versus multiple socketpairs.
Message-ID:  <200001251752.JAA04953@apollo.backplane.com>
References:  <01b601bf6696$60701930$1e80000a@avantgo.com> <200001241939.LAA91219@apollo.backplane.com> <0be801bf6715$601423d0$1e80000a@avantgo.com>

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:OK, so let's say I did spend some time implementing it in terms of semget()
:and semop().  Would you be totally apalled if the performance turned out to
:be about the same as using a single socketpair?  Do you have a very strong
:feeling that it should be significantly better.  [Again, under
:3.4-release.]  I don't think I've done anything egregious, but things don't
:seem much better.  Unfortunately, I'll have to wait until tomorrow morning
:to rip things out and make a suitable example program for posting.
:
:Actually, the performance profile does seem different (for lower loads, the
:semaphore solution seems more efficient), but the performance limits seem
:much the same between the single socketpair and semaphore versions when I
:starts using 16-20 worker processes.  It's possible that I'm doing
:..
:
:Thanks,
:scott
    
    Well, when all else fails --- go back to individual pipes.

    What else could be tried... you could try surrounding the read()
    with an flock() pair.  I don't know if flock() uses the more optimal
    wakeup code or not.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>


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