linux-kernel - CPU scheduler weirdness?

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Date:	Thu, 13 Aug 2009 02:58:35 +0200 (CEST)
From:	Marton Balint <cus@...ekas.hu>
To:	linux-kernel@...r.kernel.org
cc:	mingo@...e.hu, peterz@...radead.org
Subject: CPU scheduler weirdness?

Hi,

I have a Core2Duo E8400 CPU with 2 processor cores. Sometimes, when I run 
two cpu intensive tasks (for example "dd if=/dev/zero of=/dev/null"), 
for some reason, the two processes are scheduled to the same CPU, so I 
get one CPU core with the two CPU intensive processes and another CPU core 
which is pretty much idle. So the CPU intensive tasks run half as fast as 
they could.

Does anybody have any idea what can cause this? I thought the kernel tries 
to balance the load between multiple CPU-s. I already tried to set 
the CPU governor to "performance" on both CPU cores, but that did not 
help. I tried 2.6.30 and 2.6.31-rc5-git3 kernels. I'm attaching my 
.config.

Regards,
   Marton
View attachment "config" of type "TEXT/PLAIN" (107147 bytes)