From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Stephen Hemminger <stephen@networkplumber.org>,
Pranith Kumar <bobby.prani@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Nicholas Miell <nmiell@comcast.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>,
Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
Lai Jiangshan <laijs@cn.fujitsu.com>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
David Howells <dhowells@redhat.com>,
Michael Kerrisk <mtk.manpages@gmail.com>
Subject: Re: [PATCH v16] sys_membarrier(): system-wide memory barrier (generic, x86)
Date: Thu, 23 Apr 2015 13:45:40 +0000 (UTC) [thread overview]
Message-ID: <1146370149.34873.1429796740391.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20150422224850.76064d98@grimm.local.home>
----- Original Message -----
> On Wed, 22 Apr 2015 17:40:51 -0700
> Stephen Hemminger <stephen@networkplumber.org> wrote:
>
> > The syscall should just return 0.
> > Let the application not worry about how many CPU's are present
>
> +1
This is indeed how I implemented it initially. The nice thing
about this approach is that if the application don't care much
about the overhead of calling sys_membarrier on !SMP, returning
0 tells the application that sys_membarrier is indeed supported,
and that the application don't need to issue memory barriers on
the other target threads (compiler barrier is then sufficient),
which is correct.
I'll update the patch accordingly.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2015-04-23 13:45 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-17 15:06 [PATCH v16] sys_membarrier(): system-wide memory barrier (generic, x86) Mathieu Desnoyers
2015-04-21 11:47 ` Thomas Gleixner
2015-04-22 20:36 ` Mathieu Desnoyers
2015-04-21 16:29 ` Davidlohr Bueso
2015-04-22 19:43 ` Mathieu Desnoyers
2015-04-22 20:01 ` Michael Kerrisk (man-pages)
2015-04-22 21:01 ` Mathieu Desnoyers
2015-04-23 11:38 ` Michael Kerrisk (man-pages)
2015-04-22 20:24 ` Pranith Kumar
2015-04-22 20:40 ` Mathieu Desnoyers
2015-04-23 0:37 ` Pranith Kumar
2015-04-23 0:40 ` Stephen Hemminger
2015-04-23 2:48 ` Steven Rostedt
2015-04-23 13:45 ` Mathieu Desnoyers [this message]
2015-04-23 10:33 ` Rasmus Villemoes
2015-04-23 14:04 ` Mathieu Desnoyers
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