From: Waiman Long <waiman.long@hpe.com>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-s390@vger.kernel.org, linux-arch@vger.kernel.org,
linux-doc@vger.kernel.org, Jason Low <jason.low2@hp.com>,
Dave Chinner <david@fromorbit.com>,
Jonathan Corbet <corbet@lwn.net>,
Scott J Norton <scott.norton@hpe.com>,
Douglas Hatch <doug.hatch@hpe.com>
Subject: Re: [RFC PATCH-tip v4 10/10] locking/rwsem: Add a boot parameter to reader spinning threshold
Date: Wed, 24 Aug 2016 14:39:11 -0400 [thread overview]
Message-ID: <57BDE9CF.5030801@hpe.com> (raw)
In-Reply-To: <20160824040007.GA17186@linux-80c1.suse>
On 08/24/2016 12:00 AM, Davidlohr Bueso wrote:
> On Thu, 18 Aug 2016, Waiman Long wrote:
>
>> The default reader spining threshold is current set to 4096. However,
>> the right reader spinning threshold may vary from one system to
>> another and among the different architectures. This patch adds a new
>> kernel boot parameter to modify the threshold value. This enables
>> better tailoring to the needs of different systems as well as for
>> testing purposes.
>
> It also means that those systems could very easily be incorrectly
> tailored.
> (and worse case scenario: reboot, is obviously a terrible way to get rid
> of any issues). I very much disagree with exposing this sort of core
> stuff,
> it should work well for everyone out of the box, not relying on users to
> properly configure this.
>
> Thanks,
> Davidlohr
I also have some concern about exposing this kernel parameter as it will
be hard to tune. That is why I put it at the end to gauge the opinion of
others. I will leave this out when I send out the next version.
Cheers,
Longman
next prev parent reply other threads:[~2016-08-24 18:39 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-18 21:11 [RFC PATCH-tip v4 00/10] locking/rwsem: Enable reader optimistic spinning Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-08-18 21:11 ` [RFC PATCH-tip v4 01/10] locking/osq: Make lock/unlock proper acquire/release barrier Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-10-04 19:06 ` Davidlohr Bueso
2016-10-04 19:06 ` Davidlohr Bueso
2016-10-04 21:28 ` Jason Low
2016-10-04 21:28 ` Jason Low
2016-10-05 12:19 ` Waiman Long
2016-10-05 12:19 ` Waiman Long
2016-10-05 15:11 ` Waiman Long
2016-10-06 5:47 ` Davidlohr Bueso
2016-10-06 19:30 ` Waiman Long
2016-10-06 19:30 ` Waiman Long
2016-10-10 5:39 ` [PATCH] locking/osq: Provide proper lock/unlock and relaxed flavors Davidlohr Bueso
2016-10-10 5:39 ` Davidlohr Bueso
2016-10-06 19:31 ` [RFC PATCH-tip v4 01/10] locking/osq: Make lock/unlock proper acquire/release barrier Jason Low
2016-08-18 21:11 ` [RFC PATCH-tip v4 02/10] locking/rwsem: Stop active read lock ASAP Waiman Long
2016-10-06 18:17 ` Davidlohr Bueso
2016-10-06 18:17 ` Davidlohr Bueso
2016-10-06 21:47 ` Dave Chinner
2016-10-06 21:47 ` Dave Chinner
2016-10-06 22:51 ` Davidlohr Bueso
2016-10-07 21:45 ` Waiman Long
2016-10-07 21:45 ` Waiman Long
2016-10-09 15:17 ` Christoph Hellwig
2016-10-09 15:17 ` Christoph Hellwig
2016-10-10 6:07 ` Dave Chinner
2016-10-10 9:34 ` Christoph Hellwig
2016-10-10 9:34 ` Christoph Hellwig
2016-10-11 21:06 ` Dave Chinner
2016-10-11 21:06 ` Dave Chinner
2016-10-16 5:57 ` Christoph Hellwig
2016-10-16 5:57 ` Christoph Hellwig
2016-08-18 21:11 ` [RFC PATCH-tip v4 03/10] locking/rwsem: Make rwsem_spin_on_owner() return a tri-state value Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-08-18 21:11 ` [RFC PATCH-tip v4 04/10] locking/rwsem: Enable count-based spinning on reader Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-08-18 21:11 ` [RFC PATCH-tip v4 05/10] locking/rwsem: move down rwsem_down_read_failed function Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-08-18 21:11 ` [RFC PATCH-tip v4 06/10] locking/rwsem: Move common rwsem macros to asm-generic/rwsem_types.h Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-08-18 21:11 ` [RFC PATCH-tip v4 07/10] locking/rwsem: Change RWSEM_WAITING_BIAS for better disambiguation Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-08-19 5:57 ` Wanpeng Li
2016-08-19 5:57 ` Wanpeng Li
2016-08-19 16:21 ` Waiman Long
2016-08-19 16:21 ` Waiman Long
2016-08-22 2:15 ` Wanpeng Li
2016-08-22 2:15 ` Wanpeng Li
2016-08-18 21:11 ` [RFC PATCH-tip v4 08/10] locking/rwsem: Enable spinning readers Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-08-18 21:11 ` [RFC PATCH-tip v4 09/10] locking/rwsem: Enable reactivation of reader spinning Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-08-18 21:11 ` [RFC PATCH-tip v4 10/10] locking/rwsem: Add a boot parameter to reader spinning threshold Waiman Long
2016-08-18 21:11 ` Waiman Long
2016-08-24 1:46 ` [lkp] [locking/rwsem] INFO: rcu_preempt detected stalls on CPUs/tasks kernel test robot
2016-08-24 4:00 ` [RFC PATCH-tip v4 10/10] locking/rwsem: Add a boot parameter to reader spinning threshold Davidlohr Bueso
2016-08-24 4:00 ` Davidlohr Bueso
2016-08-24 18:39 ` Waiman Long [this message]
2016-08-24 18:39 ` Waiman Long
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