From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Alfredo Alvarez Fernandez <alfredoalvarezfernandez@gmail.com>,
Ingo Molnar <mingo@kernel.org>,
Shuah Khan <shuahkh@osg.samsung.com>,
linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Subject: Re: [lockdep] chain_key collision check triggers
Date: Fri, 3 Jun 2016 13:12:50 +0200 [thread overview]
Message-ID: <20160603111250.GB3472@osiris> (raw)
In-Reply-To: <20160603084801.GG3190@twins.programming.kicks-ass.net>
On Fri, Jun 03, 2016 at 10:48:01AM +0200, Peter Zijlstra wrote:
> On Fri, Jun 03, 2016 at 09:15:44AM +0200, Heiko Carstens wrote:
> > Hi all,
> >
> > the new lockdep chain_key collision detection code triggers quite reliably
> > on s390, so it looks like we need a different iterate_chain_key()
> > implementation?
>
> That too, I have one queued up; but if you can realiably trigger this
> that's 'good' news. Most reports so far have been one offs that people
> could not reproduce.
>
> Let me wake up a bit more, but in the meantime, the below is what I had
> queued.
>
> ---
> Subject: locking,lockdep: Use __jhash_mix for iterate_chain_key
> From: Peter Zijlstra <peterz@infradead.org>
> Date: Mon May 30 18:31:33 CEST 2016
>
> Use __jhash_mix() to mix the class_idx into the class_key. This
> function provides better mixing than the previously used, home grown
> mix function.
Ok, thanks! I'll use that then. Unfortunately the new hash function
generates 28 instead of 2 instructions on s390.
next prev parent reply other threads:[~2016-06-03 11:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20160603071544.GA3472@osiris>
2016-06-03 8:48 ` [lockdep] chain_key collision check triggers Peter Zijlstra
2016-06-03 11:12 ` Heiko Carstens [this message]
2016-06-03 11:35 ` Peter Zijlstra
2016-06-03 7:15 Heiko Carstens
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