linux-kernel - Re: Re-implement MCE log ring buffer as per-CPU ring buffer

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Message-ID: <20090424100943.GJ27264@erda.amd.com>
Date:	Fri, 24 Apr 2009 12:09:43 +0200
From:	Robert Richter <robert.richter@....com>
To:	Huang Ying <ying.huang@...el.com>
CC:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <ak@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: Re-implement MCE log ring buffer as per-CPU ring buffer

On 24.04.09 14:06:50, Huang Ying wrote:
> On Wed, 2009-04-22 at 18:16 +0800, Robert Richter wrote:
> > On 22.04.09 11:22:59, Ingo Molnar wrote:
> > > 
> > > * Huang Ying <ying.huang@...el.com> wrote:
> > > 
> > > > Re-implement MCE log ring buffer as per-CPU ring buffer for better 
> > > > scalability. Basic design is as follow:
> > > 
> > > Before changing anything substantial in the MCE code it would be 
> > > necessary to clean up and then unify the 32-bit and 64-bit side of 
> > > the MCE code first. (Which essentially means extending the 
> > > 64-bit-only code to 32-bit)
> > 
> > You may also want to consider to use the in-kernel ring_buffer api
> > (include/linux/ring_buffer.h).
> 
> It seems that ring_buffer is not NMI-safe, while mcelog buffer will be
> used in NMI context and interrupt context. When will ring_buffer to be
> NMI-safe?

You can use it in nmi context with separate read and write
buffers. See this patch description:
6dad828b76c7224a22ddc9ce7aa495d994f03b31

Not sure if somebody will make the ring_buffer non-locking.

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center
email: robert.richter@....com

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