Messages in this thread |  | | | From | (Danny ter Haar) | | Subject | Re: Q: why _less_ performance on machine with SMP then with UP kernel ? | | Date | Wed, 14 Sep 2005 06:16:53 +0000 (UTC) |
Andrew Walrond <andrew@walrond.org> wrote: >> So what is the difference between UP & SMP ? >Is there any indication in the system log that your userland (news?) software >was having problems?
Not really. The load of the machine doesn't get that high as normal. On machines that feed usenet to us (usenet ==push system) i see that we grow "backlog" (we're not accepting usenet as fast as we should).
>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
Now that you mention it, i saw this in the log file when running the SMP kernel:
newsgate kernel: mv[7024]: segfault at 00002aaaaabc3648 rip 00002aaaaaaac80e rsp 00007fffffdc17c0 error 4 It was only a oneliner, no further details.
>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.
What i did try is the following (prior on other SMP kernels) I tried binding certain processes to a certain cpu. Did the same for the irq's. Just to see if it mattered.
It didn't...
>> A very confused >One of the major symptoms of this particular bug ;)
I know, that's why a plee for help is _my_ only resort ;-) I do understand that at this level most people send in patches.
Thanks for your reply!
Will try the "echo 0" next time i boot a smp kernel.
Danny
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