Date: Wed, 30 Aug 2006 10:54:34 -0700
From: Paul Jackson <pj@sgi.com>
To: paulmck@us.ibm.com
Cc: ego@in.ibm.com, mingo@elte.hu, nickpiggin@yahoo.com.au,
       arjan@infradead.org, rusty@rustcorp.com.au, torvalds@osdl.org,
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       davej@redhat.com, dipankar@in.ibm.com, vatsa@in.ibm.com,
       ashok.raj@intel.com
Subject: Re: [RFC][PATCH 4/4] Rename lock_cpu_hotplug/unlock_cpu_hotplug
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Paul E. McKenney wrote:
> Well, my next question was going to be whether cpuset readers really
> need to exclude the writers, or whether there can be a transition
> period while the mastodon makes the change as long as it avoids stomping
> the locusts.  ;-)

The mastodon's (aka mammoths ;) may make a batch of several related
changes to the cpuset configuration.  What's important is that the
locusts see either none or all of the changes in a given batch, not
some intermediate inconsistent state, and that the locusts see the
change batches in the same order they were applied.

Off the top of my head, I doubt I care when the locusts see the
changes.  Some delay is ok, if that's your question.

But don't try too hard to fit any work you do to cpusets.  For now,
I don't plan to mess with cpuset locking anytime soon.  And when I
do next, it might be that all I need to do is to change the quick
lock held by the locusts from a mutex to an ordinary rwsem, so that
multiple readers (locusts) can access the cpuset configuration in
parallel.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.925.600.0401
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