From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Will Deacon <will.deacon@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, bigeasy@linutronix.de,
juri.lelli@redhat.com, williams@redhat.com, bristot@redhat.com,
longman@redhat.com, dave@stgolabs.net, jack@suse.com
Subject: Re: [PATCH] locking/percpu_rwsem: Rewrite to not use rwsem
Date: Wed, 30 Oct 2019 20:31:29 +0100 [thread overview]
Message-ID: <20191030193129.GA32308@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191030175231.GF5671@hirez.programming.kicks-ass.net>
On Wed, Oct 30, 2019 at 06:52:31PM +0100, Peter Zijlstra wrote:
> @@ -58,16 +72,17 @@ static inline void percpu_down_read(struct percpu_rw_semaphore *sem)
> preempt_enable();
> }
>
> -static inline int percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
> +static inline bool percpu_down_read_trylock(struct percpu_rw_semaphore *sem)
> {
> - int ret = 1;
> + bool ret = true;
>
> preempt_disable();
> /*
> * Same as in percpu_down_read().
> */
> - __this_cpu_inc(*sem->read_count);
> - if (unlikely(!rcu_sync_is_idle(&sem->rss)))
> + if (likely(!rcu_sync_is_idle(&sem->rss)))
That should obviously also loose the !
> + __this_cpu_inc(*sem->read_count);
> + else
> ret = __percpu_down_read(sem, true); /* Unconditional memory barrier */
> preempt_enable();
> /*
next prev parent reply other threads:[~2019-10-30 19:31 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 14:02 Peter Zijlstra
2019-08-05 14:43 ` Boqun Feng
2019-08-05 14:58 ` Boqun Feng
2019-08-05 15:43 ` Peter Zijlstra
2019-08-06 14:15 ` Boqun Feng
2019-08-06 16:17 ` Oleg Nesterov
2019-08-06 17:15 ` Peter Zijlstra
2019-08-07 9:56 ` Oleg Nesterov
2019-10-29 18:47 ` Peter Zijlstra
2019-10-30 14:21 ` Oleg Nesterov
2019-10-30 16:09 ` Peter Zijlstra
2019-10-30 17:52 ` Peter Zijlstra
2019-10-30 18:47 ` Peter Zijlstra
2019-10-30 19:31 ` Peter Zijlstra [this message]
2019-10-31 6:11 ` Peter Zijlstra
2019-08-07 14:45 ` Will Deacon
2019-10-29 19:06 ` Peter Zijlstra
2019-10-30 15:57 ` Oleg Nesterov
2019-10-30 16:47 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191030193129.GA32308@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=bigeasy@linutronix.de \
--cc=bristot@redhat.com \
--cc=dave@stgolabs.net \
--cc=jack@suse.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=longman@redhat.com \
--cc=mingo@kernel.org \
--cc=oleg@redhat.com \
--cc=tglx@linutronix.de \
--cc=will.deacon@kernel.org \
--cc=williams@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®