Re: [ck] Re: [announce] [patch] Voluntary Kernel Preemption Patch

From: Con Kolivas
Date: Sun Jul 11 2004 - 09:31:39 EST


Con Kolivas wrote:
Ingo Molnar wrote:

* Con Kolivas <kernel@xxxxxxxxxxx> wrote:


Ooops forgot to mention this was running reiserFS 3.6 on software
raid0 2x IDE with cfq elevator.



ok, reiserfs (and all journalling fs's) definitely need a look - as you
can see from the ext3 mods in the patch. Any chance you could try ext3
based tests? Those are the closest to my setups.


Ok I've done one better than that ;) I had wli help make some instrumentation for me to help find the remaining non preemptible kernel portions and set the cutoff to 2ms. Here is what I found:

7ms non-preemptible critical section violated 2 ms preempt threshold starting at reiserfs_sync_fs+0x2d/0xc2 and ending at reiser
fs_lookup+0xe2/0x221

9ms non-preemptible critical section violated 2 ms preempt threshold starting at reiserfs_dirty_inode+0x37/0x10e and ending at r
eiserfs_dirty_inode+0xb0/0x10e


These seem to be the two offenders. Hope this helps.

Oh and here are two different ones:

5ms non-preemptible critical section violated 2 ms preempt threshold starting at add_wait_queue+0x21/0x82 and ending at add_wait
_queue+0x4a/0x82

3ms non-preemptible critical section violated 2 ms preempt threshold starting at exit_mmap+0x1c/0x188 and ending at exit_mmap+0x
118/0x188

Con

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