Date: Wed, 28 Apr 1999 14:58:51 -0700 (PDT) From: Mike Meyer <mwm@phone.net> To: Tom <tom@uniserve.com> Cc: Matthew Reimer <mreimer@vpop.net>, freebsd-stable@freebsd.org Subject: Re: MFC pthreads before 3.2 is released? Message-ID: <Pine.BSF.4.05.9904281444550.8949-100000@guru.phone.net> In-Reply-To: <Pine.BSF.4.02A.9904281438270.18863-100000@shell.uniserve.ca>
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On Wed, 28 Apr 1999, Tom wrote: > It doesn't really depend on postgresql at all. If your process mix is > cpu intensive, you will get a benefit. If your process mix is > kernel/syscall intensive, then you won't get much benefit as only one > process can be active in the kernel at a time. Now, are your postgresql > processes cpu or kernel intensive? Depends on what you do. That I believe - that's why I listed the other things going on. The note on the Postgres list is what made me stop to think about this. The claim there was that postgres - in a syscall intensive app - actually *slowed down* with the second processor enabled. I've seen similar effects elsewhere. Early versions of Ultrix turned up better numbers on multiuser benchmarks if you turned one processor off. In practice - in that environment - someones long-running number-cruncher grabbed the second processor pretty quickly, having pretty much the same effect as disabling it. Since they wind up getting faster real-time turnaround off the 8820 than they did of the Cray X/MP-14, everyone was happy. The real question isn't how much benefit I'll see - it's whether or not there are job mixes that will cause the system to seem slower. <mike To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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