From: Will Deacon <will.deacon@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"Waiman.Long@hp.com" <Waiman.Long@hp.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"paulmck@linux.vnet.ibm.com" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH 1/5] atomics: add acquire/release/relaxed variants of some atomic operations
Date: Tue, 14 Jul 2015 16:55:06 +0100 [thread overview]
Message-ID: <20150714155500.GQ16213@arm.com> (raw)
In-Reply-To: <20150714113801.GK19282@twins.programming.kicks-ass.net>
On Tue, Jul 14, 2015 at 12:38:01PM +0100, Peter Zijlstra wrote:
> On Tue, Jul 14, 2015 at 12:31:47PM +0100, Will Deacon wrote:
> > #ifndef atomic_add
> > #define atomic_add(args...) (void)atomic_add_return_relaxed(args);
> >
> > It would mean a new architecture only has to define a barrier instruction
> > and a handful of relaxed atomics for a bare-minimum atomic.h avoiding
> > spinlocks.
>
> Look at include/asm-generic/atomic.h, all you need is a cmpxchg().
>
> We could easily change that to be cmpxchg_relaxed() and a few barriers.
Ok, I'll leave that part for now and implement your original suggestion
as a starting point.
Will
next prev parent reply other threads:[~2015-07-14 15:55 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-13 12:31 [PATCH 0/5] Add generic support for relaxed atomics Will Deacon
2015-07-13 12:31 ` Will Deacon
2015-07-13 12:31 ` [PATCH 1/5] atomics: add acquire/release/relaxed variants of some atomic operations Will Deacon
2015-07-14 10:25 ` Peter Zijlstra
2015-07-14 10:32 ` Will Deacon
2015-07-14 10:58 ` Peter Zijlstra
2015-07-14 11:08 ` Will Deacon
2015-07-14 11:08 ` Will Deacon
2015-07-14 11:24 ` Peter Zijlstra
2015-07-14 11:31 ` Will Deacon
2015-07-14 11:38 ` Peter Zijlstra
2015-07-14 11:38 ` Peter Zijlstra
2015-07-14 15:55 ` Will Deacon [this message]
2015-07-14 15:55 ` Will Deacon
2015-07-13 12:31 ` [PATCH 2/5] asm-generic: rework atomic-long.h to avoid bulk code duplication Will Deacon
2015-07-13 12:31 ` Will Deacon
2015-07-13 12:31 ` [PATCH 3/5] asm-generic: add relaxed/acquire/release variants for atomic_long_t Will Deacon
2015-07-13 12:31 ` Will Deacon
2015-07-13 12:31 ` [PATCH 4/5] lockref: remove homebrew cmpxchg64_relaxed macro definition Will Deacon
2015-07-13 12:31 ` [PATCH 5/5] locking/qrwlock: make use of acquire/release/relaxed atomics Will Deacon
2015-07-13 12:31 ` Will Deacon
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=20150714155500.GQ16213@arm.com \
--to=will.deacon@arm.com \
--cc=Waiman.Long@hp.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
/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