From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Waiman Long <waiman.long@hpe.com>, Jason Low <jason.low2@hpe.com>,
Ding Tianhong <dingtianhong@huawei.com>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <Will.Deacon@arm.com>, Ingo Molnar <mingo@redhat.com>,
Imre Deak <imre.deak@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Davidlohr Bueso <dave@stgolabs.net>,
Tim Chen <tim.c.chen@linux.intel.com>,
Terry Rudd <terry.rudd@hpe.com>,
"Paul E. McKenney" <paulmck@us.ibm.com>,
Jason Low <jason.low2@hp.com>
Subject: Re: [PATCH v4] locking/mutex: Prevent lock starvation when spinning is disabled
Date: Tue, 23 Aug 2016 14:45:19 +0200 [thread overview]
Message-ID: <20160823124519.GB10138@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+55aFz8aOeb_t2d6OqVGZeuaoS_KU+-C1=+awGdG+w7CFg13A@mail.gmail.com>
On Fri, Aug 19, 2016 at 12:45:27PM -0700, Linus Torvalds wrote:
> On Fri, Aug 19, 2016 at 12:33 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > That seems more messy to me..
>
> Can't we just say that we always spin? Are there any really valid
> cases where spinning isn't ok?
>
> We've historically disabled spinning when mutex debugging is enabled,
> but since the spinning is limited anyway, couldn't we just spin even
> with debugging enabled?
>
> I hate how these patches are trying to solve a problem that doesn't
> even happen under normal circumstances, and add special-case code for
> something that is already a special-case condition. So rather than
> adding even more special cases, could we look at _removing_ the
> special cases that cause problems instead?
So I think I have a bunch of patches that solves the fundamental issues,
_However_... they're quite invasive and would need some serious
benchmarking.
I'll post them in a separate thread as RFC..
prev parent reply other threads:[~2016-08-23 12:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-19 0:39 Jason Low
2016-08-19 4:11 ` Jason Low
2016-08-19 12:13 ` Peter Zijlstra
2016-08-19 16:57 ` Waiman Long
2016-08-19 19:33 ` Peter Zijlstra
2016-08-19 19:45 ` Linus Torvalds
2016-08-23 12:45 ` Peter Zijlstra [this message]
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