Messages in this thread | | | Date | Tue, 20 Sep 2005 15:10:09 +0200 (CEST) | From | Simon Derr <> | Subject | Re: [PATCH] cpuset semaphore depth check optimize |
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On Tue, 20 Sep 2005, Robin Holt wrote:
> Paul, > > Can you give a _short_ explanation of why notify_on_release is > essential? Could the intent be accomplished with something > like destroy on exit which then goes through and does the > remove of shildren and finally removes the cpuset? > > If we can agree on that, then the exit path becomes > if (atomic_dec_and_lock(¤t->cpuset.refcount)) { > /* Code to remove children. */ > } > which no longer needs to call a usermode helper and is _FAR_ > better in my personal biased opinion. > >
The original cpuset patch did not have a notify_on_release feature, it had an 'autoclean' feature, that did exactly what you describe.
But the locking was not clean, mostly at the filesystem level. Paul and I tried together to fix it, but at some point Paul proposed this solution, to use a usermode helper, and it seemed to be the easiest way to get out of this locking issue, so we agreed to drop the old 'autoclean' scheme.
(Even if Paul had a hard time convincing me, as I did not like the idea of this usermode helper too much).
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