From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: 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,
Davidlohr Bueso <dave@stgolabs.net>,
Dave Chinner <david@fromorbit.com>
Subject: Re: [PATCH v6 00/11] locking/rwsem: Rework rwsem-xadd & enable new rwsem features
Date: Wed, 11 Oct 2017 14:50:34 -0400 [thread overview]
Message-ID: <abbad63a-1026-6ff9-334e-9e4486b4f689@redhat.com> (raw)
In-Reply-To: <20171011184840.3uomgj3hxxzernfd@hirez.programming.kicks-ass.net>
On 10/11/2017 02:48 PM, Peter Zijlstra wrote:
> On Wed, Oct 11, 2017 at 02:01:51PM -0400, Waiman Long wrote:
>> # of Patches Reader Writer
>> Applied Locking Rate Locking Rate
>> ------------ ------------ ------------
>> 0 5,155/ 5,155/ 5,155 5,154/248,852/346,281
>> 7 5,696/ 5,697/ 5,698 113,500/215,826/320,872
>> 8 4,827/ 5,047/ 5,215 4,826/176,797/284,069
>> 9 211,276/ 509,712/1,134,007 4,894/221,839/246,818
>> 11 884,513/1,043,989/1,252,533 9,604/ 11,105/ 25,225
>>
>> It can be seen that rwsem changes from writer-preferring to
>> reader-preferring.
> A bit radically so, you almost starve the writers there.
Yes, almost, but the lock handoff code will make sure that it won't
actually get starved. That is why I added aggressive reader lock
stealing after the lock handoff code.
Cheers,
Longman
next prev parent reply other threads:[~2017-10-11 18:50 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-11 18:01 [PATCH v6 00/11] locking/rwsem: Rework rwsem-xadd & enable new rwsem features Waiman Long
2017-10-11 18:01 ` Waiman Long
2017-10-11 18:01 ` [PATCH v6 01/11] locking/rwsem: relocate rwsem_down_read_failed() Waiman Long
2017-10-11 18:01 ` Waiman Long
2017-10-11 18:01 ` [PATCH v6 02/11] locking/rwsem: Implement a new locking scheme Waiman Long
2017-10-11 18:01 ` Waiman Long
2017-10-11 18:40 ` Peter Zijlstra
2017-10-11 18:58 ` Waiman Long
2017-10-11 18:58 ` Waiman Long
2017-10-11 19:05 ` Waiman Long
2017-10-11 19:36 ` Peter Zijlstra
2017-10-11 18:01 ` [PATCH v6 03/11] locking/rwsem: Move owner setting code from rwsem.c to rwsem-xadd.h Waiman Long
2017-10-11 18:01 ` Waiman Long
2017-10-11 18:01 ` [PATCH v6 04/11] locking/rwsem: Remove kernel/locking/rwsem.h Waiman Long
2017-10-11 18:01 ` Waiman Long
2017-10-11 18:01 ` [PATCH v6 05/11] locking/rwsem: Move rwsem internal function declarations to rwsem-xadd.h Waiman Long
2017-10-11 18:01 ` Waiman Long
2017-10-11 18:01 ` [PATCH v6 06/11] locking/rwsem: Remove arch specific rwsem files Waiman Long
2017-10-11 18:01 ` Waiman Long
2017-10-11 18:01 ` [PATCH v6 07/11] locking/rwsem: Implement lock handoff to prevent lock starvation Waiman Long
2017-10-11 18:01 ` Waiman Long
2017-10-11 18:01 ` [PATCH v6 08/11] locking/rwsem: Enable readers spinning on writer Waiman Long
2017-10-11 18:01 ` Waiman Long
2017-10-11 18:02 ` [PATCH v6 09/11] locking/rwsem: Enable time-based reader lock stealing Waiman Long
2017-10-11 18:02 ` [PATCH v6 10/11] locking/rwsem: Make rwsem_spin_on_owner() return a tri-state value Waiman Long
2017-10-11 18:02 ` Waiman Long
2017-10-11 18:02 ` [PATCH v6 11/11] locking/rwsem: Enable count-based spinning on reader Waiman Long
2017-10-11 18:02 ` Waiman Long
2017-10-11 18:48 ` [PATCH v6 00/11] locking/rwsem: Rework rwsem-xadd & enable new rwsem features Peter Zijlstra
2017-10-11 18:48 ` Peter Zijlstra
2017-10-11 18:50 ` Waiman Long [this message]
2017-10-11 18:50 ` Waiman Long
2017-10-11 20:45 ` Dave Chinner
2017-10-11 20:45 ` Dave Chinner
2017-10-11 20:50 ` Dave Chinner
2017-10-11 20:50 ` Dave Chinner
2017-10-11 20:57 ` Waiman Long
2017-10-11 20:57 ` Waiman Long
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