From: Nick Piggin <npiggin@kernel.dk>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Nick Piggin <npiggin@kernel.dk>, 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>
Subject: Re: [PATCH] lglock: make lg_lock_global() actually lock globally
Date: Fri, 27 Aug 2010 15:51:05 +1000 [thread overview]
Message-ID: <20100827055105.GA3857@amd> (raw)
In-Reply-To: <1282823139.1975.689.camel@laptop>
On Thu, Aug 26, 2010 at 01:45:39PM +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?
Well, as is implemented.
> 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.
I would much prefer the rules to be simpler and easier for all
other kernel code, and keep complexity and overheads in cpu
plug/unplug.
I don't see what is so nice about stop_machine()less cpu plug/unplug
or module unload. Module load definitely is nice because you can
have a lot of modules and on demand loading from non-privileged
operations.
next prev parent reply other threads:[~2010-08-27 5:51 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-25 19:28 [PATCH] lglock: make lg_lock_global() actually lock globally Jonathan Corbet
2010-08-25 20:00 ` Linus Torvalds
2010-08-25 20:16 ` Jonathan Corbet
2010-08-26 4:23 ` Nick Piggin
2010-08-26 8:55 ` Tejun Heo
2010-08-26 9:46 ` Nick Piggin
2010-08-26 9:49 ` Tejun Heo
2010-08-26 9:50 ` Tejun Heo
2010-08-26 10:08 ` Peter Zijlstra
2010-08-26 11:38 ` Nick Piggin
2010-08-26 11:45 ` Peter Zijlstra
2010-08-26 11:49 ` Peter Zijlstra
2010-08-27 5:51 ` Nick Piggin [this message]
2010-08-27 7:57 ` Peter Zijlstra
2010-08-27 7:59 ` Peter Zijlstra
2010-08-26 10:08 ` Peter Zijlstra
-- strict thread matches above, loose matches on Subject: below --
2010-09-08 22:54 Jonathan Corbet
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