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Date: Sun, 12 Dec 2010 16:11:12 +0100 From: Ralf Hildebrandt <Ralf.Hildebrandt@...rite.de> To: linux-kernel@...r.kernel.org Subject: Costly Context Switches I recently made a parallel installation of dovecot-2.0 on my mailbox server, which is running dovecot-1.2 without any problems whatsoever. Using dovecot-2.0 on the same hardware, same kernel, with the same users and same mailboxes and usage behaviour results in an immense increase in the load numbers. Switching back to 1.2 results in a immediate decrease of the load back to "normal" numbers. This is mainly due to a 10-20 fold increase of the number of context switches. The same problem has been reported independently by Cor Bosman of XS4All, on different hardware (64bit instead of 32bit, real hardware instead of virtual hardware). So, now the kernel related question: How can I find out WHY the context switches are happening? Are there any "in kernel" statistics I could look at? I'm running an Ubuntu kernel: 2.6.32-27-generic-pae #49-Ubuntu SMP -- Ralf Hildebrandt Geschäftsbereich IT | Abteilung Netzwerk Charité - Universitätsmedizin Berlin Campus Benjamin Franklin Hindenburgdamm 30 | D-12203 Berlin Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962 ralf.hildebrandt@...rite.de | http://www.charite.de -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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