From: Peter Zijlstra <peterz@infradead.org>
To: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Intel graphics driver community testing & development
<intel-gfx@lists.freedesktop.org>,
Linux kernel development <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
David Hildenbrand <dahi@linux.vnet.ibm.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
"Gautham R. Shenoy" <ego@linux.vnet.ibm.com>,
Chris Wilson <chris@chris-wilson.co.uk>,
Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH] [RFC] kernel/cpu: Use lockref for online CPU reference counting
Date: Tue, 16 Feb 2016 10:14:40 +0100 [thread overview]
Message-ID: <20160216091440.GT6357@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1455612576.4977.11.camel@linux.intel.com>
On Tue, Feb 16, 2016 at 10:49:36AM +0200, Joonas Lahtinen wrote:
> I originally thought of implementing this more similar to what you
> specify, but then I came across a discussion in the mailing list where
> it was NAKed adding more members to task_struct;
>
> http://comments.gmane.org/gmane.linux.kernel/970273
>
> Adding proper recursion (the way my initial implementation was going)
> got ugly without modifying task_struct because get_online_cpus() is a
> speed critical code path.
Yeah, just don't let Linus hear you say that. get_online_cpus() is _not_
considered performance critical.
> So I'm all for fixing the current code in a different way if that will
> then be merged.
So I'm not sure why you're poking at this horror show to begin with.
ISTR you mentioning a lockdep splat for SKL, but failed to provide
detail.
Making the hotplug lock _more_ special to fix that is just wrong. Fix
the retarded locking that lead to it.
next prev parent reply other threads:[~2016-02-16 9:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-15 12:36 Joonas Lahtinen
2016-02-15 14:17 ` Peter Zijlstra
2016-02-15 17:06 ` Peter Zijlstra
2016-02-16 8:49 ` Joonas Lahtinen
2016-02-16 9:14 ` Peter Zijlstra [this message]
2016-02-16 10:51 ` Joonas Lahtinen
2016-02-16 11:07 ` Peter Zijlstra
2016-02-17 12:47 ` Joonas Lahtinen
2016-02-17 14:20 ` Peter Zijlstra
2016-02-17 16:13 ` Daniel Vetter
2016-02-17 16:14 ` Peter Zijlstra
2016-02-17 16:33 ` [Intel-gfx] " Daniel Vetter
2016-02-17 16:37 ` Peter Zijlstra
2016-02-18 10:39 ` Joonas Lahtinen
2016-02-18 10:54 ` Joonas Lahtinen
2016-02-15 17:18 ` [Intel-gfx] " Daniel Vetter
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