Re: Preempt Threshold Measurements

[Con Kolivas]

Andrew Morton writes:

> Con Kolivas <kernel@xxxxxxxxxxx> wrote:
> > Certainly the do_munmap and exit_mmap seem to be repeat offenders on my 
> > machine too (more the latter in my case).
>
> This is a false positive.  Nothing is setting need_resched(), so
> unmap_vmas() doesn't bother dropping the lock.

Ok well excluding do_munmap and exit_mmap the ones that have shown up 
(some more frequently than others) are: 

6ms at ksoftirqd+0x6b
2ms at sys_ioctl+0x47
2ms at b44_open
6ms at fget+0x28
2ms at write_ordered_buffers+0x37
4ms at blkdev_put+0x48
5ms at add_wait_queue+0x21
4ms at blkdev_put+0x48

and you were right; eventually the reiserfs ones showed up again at 6-8ms

Now which of the above are not false positives and should I try to extract 
the exact locations of them?

Con

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