lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1357219477.10284.23.camel@gandalf.local.home>
Date:	Thu, 03 Jan 2013 08:24:37 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jan Beulich <JBeulich@...e.com>
Cc:	Rik van Riel <riel@...hat.com>, eric.dumazet@...il.com,
	therbert@...gle.com, walken@...gle.com, jeremy@...p.org,
	tglx@...utronix.de, aquini@...hat.com, lwoodman@...hat.com,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 3/3 -v2] x86,smp: auto tune spinlock backoff delay
 factor

On Thu, 2013-01-03 at 09:05 +0000, Jan Beulich wrote:

> > How much bus traffic do monitor/mwait cause behind the scenes?
> 
> I would suppose that this just snoops the bus for writes, but the
> amount of bus traffic involved in this isn't explicitly documented.
> 
> One downside of course is that unless a spin lock is made occupy
> exactly a cache line, false wakeups are possible.

And that would probably be very likely, as the whole purpose of Rik's
patches was to lower cache stalls due to other CPUs pounding on spin
locks that share the cache line of what is being protected (and
modified).

-- Steve


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ