Date: Sat, 22 Apr 2000 23:25:52 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Kent Stewart <kstewart@3-cities.com> Cc: Michael Bacarella <mbac@nyct.net>, Alfred Perlstein <bright@wintelcom.net>, Kevin Day <toasty@dragondata.com>, hackers@FreeBSD.ORG Subject: Re: Double buffered cp(1) Message-ID: <200004230625.XAA58076@apollo.backplane.com> References: <Pine.BSF.4.21.0004221320250.38433-100000@bsd1.nyct.net> <200004221736.KAA55484@apollo.backplane.com> <3901F277.66DDDDAF@3-cities.com> <200004222317.QAA56834@apollo.backplane.com> <39026874.F652A405@3-cities.com>
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:You are right but that is because I haven't started keeping record on
:4.0-Stable and we were comparing apples and oranges. A buildworld of
:3.4-Stable required around 2000u seconds using gcc-2.8.2 on my system.
:Setiathome, which is running at a nice of 19, still consumed 90% of
:the cpu. A buildworld on 4.0-Stable required 3500u seconds using
:gcc-2.95.2 and setiathome didn't accrue any appreciable cpu time
:during the build. There were definitely some changes there :).
:
:Kent
:
:--
:Kent Stewart
:Richland, WA
Both 3.4 and 4.0 buildworlds are cpu-bound. If you are trying to test
buildworlds, then don't run setiathome (or anything else) while doing
the test... it will skew the results of your tests due to differences
between the 3.4 and 4.x schedulers (specifically, various scheduler
bugs were fixed in 4.x that effect niced cpu-bound background programs
such as setiathome, giving them way, way too much cpu).
It is simply impossible to fairly measure I/O performance in the
presence of unrelated background-running programs, especially under 3.x.
And even though 4.x does a better job of it, it will still skew the
results.
-Matt
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