On Wed, 2007-11-21 at 15:34 -0500, Jie Chen wrote:Hi, Peter:
It is clearly that the synchronization overhead increases as the number of threads increases in the kernel 2.6.21. But the synchronization overhead actually decreases as the number of threads increases in the kernel 2.6.23.8 (We observed the same behavior on kernel 2.6.22 as well). This certainly is not a correct behavior. The kernels are configured with CONFIG_SMP, CONFIG_NUMA, CONFIG_SCHED_MC, CONFIG_PREEMPT_NONE, CONFIG_DISCONTIGMEM set. The complete kernel configuration file is in the attachment of this e-mail.
From what we have read, there was a new scheduler (CFS) appeared from 2.6.22. We are not sure whether the above behavior is caused by the new scheduler.
If I read this correctly, you say that: .22 is the first bad one right?
The new scheduler (CFS) was introduced in .23, so it seems another
change would be responsible for this.