From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
Davidlohr Bueso <dave@stgolabs.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
huang ying <huang.ying.caritas@gmail.com>
Subject: Re: [PATCH v8 14/19] locking/rwsem: Enable time-based spinning on reader-owned rwsem
Date: Tue, 4 Jun 2019 11:03:09 +0200 [thread overview]
Message-ID: <20190604090309.GG3402@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190520205918.22251-15-longman@redhat.com>
On Mon, May 20, 2019 at 04:59:13PM -0400, Waiman Long wrote:
> +static inline void rwsem_set_nonspinnable(struct rw_semaphore *sem)
> +{
> + long owner = atomic_long_read(&sem->owner);
> +
> + while (owner & RWSEM_READER_OWNED) {
> + if (owner & RWSEM_NONSPINNABLE)
> + break;
> + owner = atomic_long_cmpxchg(&sem->owner, owner,
> + owner | RWSEM_NONSPINNABLE);
> + }
> +}
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -206,12 +206,13 @@ static inline void rwsem_set_nonspinnabl
{
long owner = atomic_long_read(&sem->owner);
- while (owner & RWSEM_READER_OWNED) {
+ do {
+ if (!(owner & RWSEM_READER_OWNED))
+ break;
if (owner & RWSEM_NONSPINNABLE)
break;
- owner = atomic_long_cmpxchg(&sem->owner, owner,
- owner | RWSEM_NONSPINNABLE);
- }
+ } while (!atomic_long_try_cmpxchg(&sem->owner, &owner,
+ owner | RWSEM_NONSPINNABLE));
}
/*
next prev parent reply other threads:[~2019-06-04 9:03 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 20:58 [PATCH v8 00/19] locking/rwsem: Rwsem rearchitecture part 2 Waiman Long
2019-05-20 20:59 ` [PATCH v8 01/19] locking/rwsem: Make owner available even if !CONFIG_RWSEM_SPIN_ON_OWNER Waiman Long
2019-06-17 14:23 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 02/19] locking/rwsem: Remove rwsem_wake() wakeup optimization Waiman Long
2019-06-17 14:24 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 03/19] locking/rwsem: Implement a new locking scheme Waiman Long
2019-06-17 14:24 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 04/19] locking/rwsem: Merge rwsem.h and rwsem-xadd.c into rwsem.c Waiman Long
2019-06-17 14:25 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 05/19] locking/rwsem: Code cleanup after files merging Waiman Long
2019-06-17 14:26 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 06/19] locking/rwsem: Make rwsem_spin_on_owner() return owner state Waiman Long
2019-06-17 14:27 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 07/19] locking/rwsem: Implement lock handoff to prevent lock starvation Waiman Long
2019-06-04 3:03 ` Yuyang Du
2019-06-04 3:26 ` Yuyang Du
2019-06-04 9:12 ` Boqun Feng
2019-06-04 16:00 ` Waiman Long
2019-06-05 7:48 ` Yuyang Du
2019-06-04 13:21 ` Waiman Long
2019-06-17 14:27 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 08/19] locking/rwsem: Always release wait_lock before waking up tasks Waiman Long
2019-06-17 14:28 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 09/19] locking/rwsem: More optimal RT task handling of null owner Waiman Long
2019-06-17 14:29 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 10/19] locking/rwsem: Wake up almost all readers in wait queue Waiman Long
2019-06-17 14:29 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 11/19] locking/rwsem: Clarify usage of owner's nonspinaable bit Waiman Long
2019-06-17 14:30 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 12/19] locking/rwsem: Enable readers spinning on writer Waiman Long
2019-06-17 14:31 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 13/19] locking/rwsem: Make rwsem->owner an atomic_long_t Waiman Long
2019-06-04 8:52 ` Peter Zijlstra
2019-06-04 15:44 ` Waiman Long
2019-06-17 14:32 ` [tip:locking/core] " tip-bot for Waiman Long
2019-07-19 18:45 ` [PATCH v8 13/19] " Luis Henriques
2019-07-19 19:32 ` Waiman Long
2019-07-19 19:45 ` Luis Henriques
2019-07-19 20:14 ` Waiman Long
2019-07-19 19:51 ` Linus Torvalds
2019-07-20 8:41 ` Luis Henriques
2019-07-20 9:32 ` Luis Henriques
2019-07-20 9:45 ` Luis Henriques
2019-07-20 11:10 ` Peter Zijlstra
2019-07-20 15:04 ` Waiman Long
2019-07-21 20:49 ` Luis Henriques
2019-07-23 2:57 ` Waiman Long
2019-07-25 15:59 ` [tip:locking/core] locking/rwsem: Don't call owner_on_cpu() on read-owner tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 14/19] locking/rwsem: Enable time-based spinning on reader-owned rwsem Waiman Long
2019-06-04 9:03 ` Peter Zijlstra [this message]
2019-06-04 16:54 ` Waiman Long
2019-06-17 14:32 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 15/19] locking/rwsem: Adaptive disabling of reader optimistic spinning Waiman Long
2019-06-04 9:10 ` Peter Zijlstra
2019-06-04 17:28 ` Waiman Long
2019-06-04 9:14 ` Peter Zijlstra
2019-06-04 17:29 ` Waiman Long
2019-06-04 9:20 ` Peter Zijlstra
2019-06-04 17:30 ` Waiman Long
2019-06-04 17:38 ` Peter Zijlstra
2019-06-04 18:04 ` Waiman Long
2019-06-04 18:14 ` Peter Zijlstra
2019-06-04 18:21 ` Waiman Long
2019-06-05 18:13 ` Waiman Long
2019-06-05 20:19 ` Peter Zijlstra
2019-06-05 20:52 ` Linus Torvalds
2019-06-06 8:03 ` Peter Zijlstra
2019-06-06 8:11 ` Peter Zijlstra
2019-06-04 10:58 ` Peter Zijlstra
2019-06-17 14:33 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 16/19] locking/rwsem: Guard against making count negative Waiman Long
2019-06-11 13:11 ` Peter Zijlstra
2019-06-11 13:27 ` Peter Zijlstra
2019-06-11 13:13 ` Peter Zijlstra
2019-06-17 14:34 ` [tip:locking/core] " tip-bot for Waiman Long
2019-05-20 20:59 ` [PATCH v8 17/19] locking/rwsem: Merge owner into count on x86-64 Waiman Long
2019-06-04 9:45 ` Peter Zijlstra
2019-06-04 15:47 ` Waiman Long
2019-06-04 17:02 ` Peter Zijlstra
2019-06-04 17:06 ` Waiman Long
2019-06-04 17:18 ` Peter Zijlstra
2019-05-20 20:59 ` [PATCH v8 18/19] locking/rwsem: Remove redundant computation of writer lock word Waiman Long
2019-05-20 20:59 ` [PATCH v8 19/19] locking/rwsem: Disable preemption in down_read*() if owner in count Waiman Long
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