Subject: Re: [PATCH] lglock: make lg_lock_global() actually lock globally
From: Peter Zijlstra <peterz@infradead.org>
To: Nick Piggin <npiggin@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Rusty Russell <rusty@rustcorp.com.au>,
        Al Viro <viro@zeniv.linux.org.uk>, LKML <linux-kernel@vger.kernel.org>
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Date: Thu, 26 Aug 2010 13:49:00 +0200
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On Thu, 2010-08-26 at 13:45 +0200, Peter Zijlstra wrote:
> On Thu, 2010-08-26 at 21:38 +1000, Nick Piggin wrote:
> > I think for CPU plug, stop_machine is reasonable (especially
> > considering it is required in unload, which means any frequent
> > amount of cpu plug activity already will require stop_machine to
> > run anyway). 
> 
> How is it required? 
> 
> Its currently implemented as such, and its sure a lot easier to do that
> way, but I could imagine that unplugging a CPU could be done without it.

Not that reworking unplug to not use stop_machine is anywhere near my
todo list, but it would be really nice to have ;-)
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