From: Will Deacon <will@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Kogan <alex.kogan@oracle.com>,
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,
steven.sistare@oracle.com, linux-kernel@vger.kernel.org,
rahul.x.yadav@oracle.com, mingo@redhat.com, bp@alien8.de,
hpa@zytor.com, longman@redhat.com, tglx@linutronix.de,
daniel.m.jordan@oracle.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v7 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock
Date: Wed, 22 Jan 2020 08:58:17 +0000 [thread overview]
Message-ID: <20200122085816.GB15537@willie-the-truck> (raw)
In-Reply-To: <20200121202919.GM11457@worktop.programming.kicks-ass.net>
On Tue, Jan 21, 2020 at 09:29:19PM +0100, Peter Zijlstra wrote:
>
> various notes and changes in the below.
>
> ---
>
> Index: linux-2.6/kernel/locking/qspinlock.c
> ===================================================================
> --- linux-2.6.orig/kernel/locking/qspinlock.c
> +++ linux-2.6/kernel/locking/qspinlock.c
> @@ -598,10 +598,10 @@ EXPORT_SYMBOL(queued_spin_lock_slowpath)
> #define _GEN_CNA_LOCK_SLOWPATH
>
> #undef pv_wait_head_or_lock
> -#define pv_wait_head_or_lock cna_pre_scan
> +#define pv_wait_head_or_lock cna_wait_head_or_lock
>
> #undef try_clear_tail
> -#define try_clear_tail cna_try_change_tail
> +#define try_clear_tail cna_try_clear_tail
>
> #undef mcs_pass_lock
> #define mcs_pass_lock cna_pass_lock
> Index: linux-2.6/kernel/locking/qspinlock_cna.h
> ===================================================================
> --- linux-2.6.orig/kernel/locking/qspinlock_cna.h
> +++ linux-2.6/kernel/locking/qspinlock_cna.h
> @@ -8,37 +8,37 @@
> /*
> * Implement a NUMA-aware version of MCS (aka CNA, or compact NUMA-aware lock).
> *
> - * In CNA, spinning threads are organized in two queues, a main queue for
> + * In CNA, spinning threads are organized in two queues, a primary queue for
> * threads running on the same NUMA node as the current lock holder, and a
> - * secondary queue for threads running on other nodes. Schematically, it
> - * looks like this:
> + * secondary queue for threads running on other nodes. Schematically, it looks
> + * like this:
> *
> * cna_node
> - * +----------+ +--------+ +--------+
> - * |mcs:next | -> |mcs:next| -> ... |mcs:next| -> NULL [Main queue]
> - * |mcs:locked| -+ +--------+ +--------+
> + * +----------+ +--------+ +--------+
> + * |mcs:next | --> |mcs:next| --> ... |mcs:next| --> NULL [Primary queue]
> + * |mcs:locked| -. +--------+ +--------+
> * +----------+ |
> - * +----------------------+
> - * \/
> + * `----------------------.
> + * v
> * +--------+ +--------+
> - * |mcs:next| -> ... |mcs:next| [Secondary queue]
> + * |mcs:next| --> ... |mcs:next| [Secondary queue]
> * +--------+ +--------+
> * ^ |
> - * +--------------------+
> + * `--------------------'
> *
> - * N.B. locked = 1 if secondary queue is absent. Othewrise, it contains the
> + * N.B. locked := 1 if secondary queue is absent. Othewrise, it contains the
If we're redoing the comment, please can you s/Othewrise/Otherwise/ at the
same time? It catches me every time I read it!
Will
next prev parent reply other threads:[~2020-01-22 8:58 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-25 21:07 [PATCH v7 0/5] Add NUMA-awareness to qspinlock Alex Kogan
2019-11-25 21:07 ` [PATCH v7 1/5] locking/qspinlock: Rename mcs lock/unlock macros and make them more generic Alex Kogan
2020-01-22 9:15 ` Peter Zijlstra
[not found] ` <C608A39E-CAFC-4C79-9EB6-3DFD9621E3F6@oracle.com>
2020-01-25 11:23 ` Peter Zijlstra
2019-11-25 21:07 ` [PATCH v7 2/5] locking/qspinlock: Refactor the qspinlock slow path Alex Kogan
2019-11-25 21:07 ` [PATCH v7 3/5] locking/qspinlock: Introduce CNA into the slow path of qspinlock Alex Kogan
2019-12-06 17:21 ` Waiman Long
2019-12-06 19:50 ` Alex Kogan
2020-01-21 20:29 ` Peter Zijlstra
2020-01-22 8:58 ` Will Deacon [this message]
2020-01-22 9:22 ` Peter Zijlstra
2020-01-22 9:51 ` Peter Zijlstra
2020-01-22 17:04 ` Peter Zijlstra
2020-01-23 9:00 ` Peter Zijlstra
2020-01-30 22:01 ` Alex Kogan
2020-01-31 13:35 ` Peter Zijlstra
2020-01-31 18:33 ` Alex Kogan
2019-11-25 21:07 ` [PATCH v7 4/5] locking/qspinlock: Introduce starvation avoidance into CNA Alex Kogan
2019-12-06 18:09 ` Waiman Long
2019-11-25 21:07 ` [PATCH v7 5/5] locking/qspinlock: Introduce the shuffle reduction optimization " Alex Kogan
2019-12-06 22:00 ` Waiman Long
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