Date: Fri, 30 Jan 2009 15:13:38 +0100 From: Ivan Voras <ivoras@freebsd.org> To: mister.olli@googlemail.com Cc: freebsd-xen@freebsd.org, Julian Stecklina <js@alien8.de> Subject: Re: kern.hz = 10 Message-ID: <9bbcef730901300613h1d4a3565xd6a0cbea4f70af00@mail.gmail.com> In-Reply-To: <1233319967.24925.19.camel@phoenix.blechhirn.net> References: <87ocxp1tym.fsf@tabernacle.localnet> <1233285247.24925.4.camel@phoenix.blechhirn.net> <871vul1nqk.fsf@tabernacle.localnet> <9bbcef730901300214s19c91071vf9241cd7cd40ba57@mail.gmail.com> <1233319967.24925.19.camel@phoenix.blechhirn.net>
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2009/1/30 Mister Olli <mister.olli@googlemail.com>: > I've run on 100HZ quite some time now and did have the impression that > 8-CURRENT is slow. It's even faster on copy processes as 7 under VMware > on a host machine which is 3 years younger... This might or (probably) might not be due to HZ. If you're interested in testing, here's what you should do: 1. compile a 8-CURRENT kernel without debugging (WITNESS, INVARIANTS & their support kernel options) 2. compile a 8-CURRENT world without malloc debugging (see http://wiki.freebsd.org/DefaultDebuggingKnobs) 3. run some repeatable tests - I'd suggest some file system benchmarks on a RAM (md) drive, see http://man.freebsd.org/md like bonnie++ and blogbench and some network tests with iperf 4. change HZ in loader.conf and test again, in exactly the same way as before (in 3.) Benchmarks that are not repeatable are useless. Repeatable means by you (so e.g. the host machine must be in the same state - no additional programs running, etc., see http://wiki.freebsd.org/BenchmarkAdvice) and by others when following your steps exactly.
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