Messages in this thread | | | From | Andrew Walrond <> | Subject | Re: Q: why _less_ performance on machine with SMP then with UP kernel ? | Date | Tue, 13 Sep 2005 22:54:15 +0100 |
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On Tuesday 13 September 2005 22:12, Danny ter Haar wrote: > > From yesterday till 10:30am i ran 2.6.13.1 in UP mode. > As you can see blue (==incoming traffic) is fairly constant. > This morning i compiled/installed 2.6.14-rc1-smp. > I let it ran till 12:15 but it's clear that it can't keep up > with the flow of data. I rebooted to 2.6.14-rc1 (UP) and that > keeps up with the data just fine. > > So what is the difference between UP & SMP ?
Is there any indication in the system log that your userland (news?) software was having problems? It may be entirely unrelated to your problem, but you should anyway be aware of a nasty unresolved issue with all smp kernels >= 2.6.12 on smp x86_64 systems:
http://bugzilla.kernel.org/show_bug.cgi?id=4851
If you have any indication of userland problems, you might try echo 0 > /proc/sys/kernel/randomize_va_space which much reduces (but seemingly does not completely remove) this issue for most people.
> > A very confused >
One of the major symptoms of this particular bug ;)
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