From: Waiman Long <Waiman.Long@hp.com>
To: Will Deacon <will.deacon@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
David Howells <dhowells@redhat.com>,
Dave Jones <davej@redhat.com>,
Clark Williams <williams@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"Chandramouleeswaran, Aswin" <aswin@hp.com>,
Davidlohr Bueso <davidlohr.bueso@hp.com>,
"Norton, Scott J" <scott.norton@hp.com>,
Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH v2 optional 3/3] mutex: back out architecture specific check for negative mutex count
Date: Tue, 16 Apr 2013 08:10:53 -0400 [thread overview]
Message-ID: <516D3FCD.9060703@hp.com> (raw)
In-Reply-To: <20130416100505.GD31156@mudshark.cambridge.arm.com>
On 04/16/2013 06:05 AM, Will Deacon wrote:
> On Mon, Apr 15, 2013 at 03:37:59PM +0100, Waiman Long wrote:
>> If it is confirmed that all the supported architectures can allow a
>> negative mutex count without incorrect behavior, we can then back
>> out the architecture specific change and allow the mutex count to
>> go to any negative number. That should further reduce contention for
>> non-x86 architecture.
>>
>> If this is not the case, this patch should be dropped.
> A good starting point might be to look at the asm-generic mutex
> implementations, which clears up the majority of architectures. A cursory
> glance at mutex-dec.h suggests that it's OK to me...
I think the generic version is fine with negative mutex count. However,
it is the architecture specific versions (we have 22 of them as of 3.8)
that I am worry about. I just don't have enough know-how and test
machines to verify that.
Regards,
Longman
next prev parent reply other threads:[~2013-04-16 12:10 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-15 14:37 [PATCH 0/3 v2] mutex: Improve mutex performance by doing less atomic-ops & better spinning Waiman Long
2013-04-15 14:37 ` [PATCH v2 1/3] mutex: Make more scalable by doing less atomic operations Waiman Long
2013-04-15 14:45 ` Rik van Riel
2013-04-15 14:37 ` [PATCH v2 2/3] mutex: Queue mutex spinners with MCS lock to reduce cacheline contention Waiman Long
2013-04-15 16:27 ` Rik van Riel
2013-04-16 4:24 ` Davidlohr Bueso
2013-04-16 12:05 ` Waiman Long
2013-04-16 9:10 ` Ingo Molnar
2013-04-16 14:26 ` Waiman Long
2013-04-17 7:50 ` Ingo Molnar
2013-04-15 14:37 ` [PATCH v2 optional 3/3] mutex: back out architecture specific check for negative mutex count Waiman Long
2013-04-16 10:05 ` Will Deacon
2013-04-16 12:10 ` Waiman Long [this message]
2013-04-16 9:12 ` [PATCH 0/3 v2] mutex: Improve mutex performance by doing less atomic-ops & better spinning Ingo Molnar
2013-04-16 11:49 ` Waiman Long
2013-04-16 13:09 ` Ingo Molnar
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=516D3FCD.9060703@hp.com \
--to=waiman.long@hp.com \
--cc=aswin@hp.com \
--cc=davej@redhat.com \
--cc=davidlohr.bueso@hp.com \
--cc=dhowells@redhat.com \
--cc=hpa@zytor.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=riel@redhat.com \
--cc=scott.norton@hp.com \
--cc=tglx@linutronix.de \
--cc=will.deacon@arm.com \
--cc=williams@redhat.com \
--cc=x86@kernel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.