Re: [PATCH 2.6.12-rc4] cpuset exit NULL dereference fix
From: Paul Jackson
Date: Fri May 27 2005 - 03:47:19 EST
> > Would it make sense, Simon, to recommend to Andrew that
> > he take the simple patch I submitted yesterday ...
> > Then, when we understand ... offer up a second patch?
> Of course !
Ok - I'll resubmit that patch. Hopefully you can reply to that
resubmitted patch with an "Acked-by: ..."
Andrew withdrew the original patch, when it became a matter needing
> My point is only that if you think there is a scaling problem in
> taking cpuset_sem for each call to cpuset_exit(), that scaling problem
> won't disappear by taking cpuset_sem only for 'notify_on_remove' cpusets,
Yes - that is a good and valid point.
I also lack any real evidence of a scaling problem. It's just a
theoretical concern. My unreliable weather forecast is that it will be
a while before it's a serious concern.
This means I am willing to take simple measures to minimize the concern,
but I'd prefer to await hard evidence of the problem before trying more
My impression is that cpusets has two classes of users:
1) Extreme HPC apps, scaling to hundreds or thousands of CPUs, and
2) More mixed or service oriented apps, with less extreme scaling.
I also suspect that it is the second class that most requires
notify_on_release. The extreme HPC guys have less need for
So I find a solution that lets one trade off extreme scaling versus
heavier use of notify_on_release to be appealing, if it can be done
trivially, as this patch does.
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@xxxxxxxxxxxx> 1.650.933.1373, 1.925.600.0401
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/