From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: linux-arch@vger.kernel.org, guohanjun@huawei.com, arnd@arndb.de,
dave.dice@oracle.com, jglauber@marvell.com, x86@kernel.org,
will.deacon@arm.com, linux@armlinux.org.uk,
linux-kernel@vger.kernel.org, rahul.x.yadav@oracle.com,
mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
Alex Kogan <alex.kogan@oracle.com>,
steven.sistare@oracle.com, tglx@linutronix.de,
daniel.m.jordan@oracle.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
Date: Wed, 17 Jul 2019 09:44:35 +0200 [thread overview]
Message-ID: <20190717074435.GU3419@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <9fa54e98-0b9b-0931-db32-c6bd6ccfe75b@redhat.com>
On Tue, Jul 16, 2019 at 10:16:29PM -0400, Waiman Long wrote:
> A simple graphic to illustrate those queues will help too, for example
Very much yes!
> /*
> * MCS lock holder
> * ===============
> * mcs_node
> * +--------+ +----+ +----+
> * | next | ---> |next| -> ... |next| -> NULL [Main queue]
> * | locked | -+ +----+ +----+
> * +--------+ |
> * | +----+ +----+
> * +-> |next| -> ... |next| -> X [Secondary queue]
> * cna_node +----+ +----+
> * +--------* ^
> * | tail | ----------------------+
> * +--------*
Almost; IIUC that cna_node is the same as the one from locked, so you
end up with something like:
> * mcs_node
> * +--------+ +----+ +----+
> * | next | ---> |next| -> ... |next| -> NULL [Main queue]
> * | locked | -+ +----+ +----+
> * +--------+ |
> * | +---------+ +----+
> * +-> |mcs::next| -> ... |next| -> NULL [Secondary queue]
> * |cna::tail| -+ +----+
> * +---------+ | ^
> * +--------+
> *
> * N.B. locked = 1 if secondary queue is absent.
> */
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next prev parent reply other threads:[~2019-07-17 7:44 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-15 19:25 [PATCH v3 0/5] Add NUMA-awareness to qspinlock Alex Kogan
2019-07-15 19:25 ` [PATCH v3 1/5] locking/qspinlock: Make arch_mcs_spin_unlock_contended more generic Alex Kogan
2019-07-16 10:23 ` Peter Zijlstra
2019-07-15 19:25 ` [PATCH v3 2/5] locking/qspinlock: Refactor the qspinlock slow path Alex Kogan
2019-07-16 10:20 ` Peter Zijlstra
2019-07-16 14:53 ` Alex Kogan
2019-07-16 15:58 ` Peter Zijlstra
2019-07-15 19:25 ` [PATCH v3 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Alex Kogan
2019-07-15 21:30 ` Waiman Long
2019-07-16 11:04 ` Peter Zijlstra
2019-07-16 14:26 ` Alex Kogan
2019-07-16 14:44 ` Waiman Long
[not found] ` <aa73b86d-902a-bb6f-d372-8645c8299a6d@redhat.com>
[not found] ` <C1C55A40-FDB1-43B5-B551-F9B8BE776DF8@oracle.com>
2019-07-16 14:50 ` Waiman Long
2019-07-17 17:44 ` Alex Kogan
2019-07-17 17:58 ` Waiman Long
2019-07-16 11:05 ` Peter Zijlstra
2019-07-16 14:30 ` Alex Kogan
2019-07-16 15:50 ` Peter Zijlstra
2019-07-16 17:19 ` Alex Kogan
2019-07-16 18:47 ` Peter Zijlstra
2019-07-17 8:39 ` Peter Zijlstra
2019-07-17 8:59 ` Peter Zijlstra
2019-07-17 14:52 ` Alex Kogan
[not found] ` <FFC2D45A-24B3-40E1-ABBB-1D696E830B23@oracle.com>
2019-07-17 15:09 ` Peter Zijlstra
2019-07-17 2:16 ` Waiman Long
2019-07-17 7:44 ` Peter Zijlstra [this message]
2019-07-17 13:35 ` Waiman Long
2019-07-17 14:42 ` Alex Kogan
2019-07-15 19:25 ` [PATCH v3 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Alex Kogan
2019-07-16 15:59 ` Peter Zijlstra
2019-07-15 19:25 ` [PATCH v3 5/5] locking/qspinlock: Introduce the shuffle reduction optimization " Alex Kogan
2019-07-16 11:47 ` [PATCH v3 0/5] Add NUMA-awareness to qspinlock Nicholas Piggin
[not found] ` <7D29555E-8F72-4EDD-8A87-B1A59C3945A6@oracle.com>
2019-07-16 23:07 ` Nicholas Piggin
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