linux-kernel - Re: [PATCH -v5] x86: MCE: Re-implement MCE log ring buffer as per-CPU ring buffer

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Date:	Mon, 8 Jun 2009 10:52:59 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Huang Ying <ying.huang@...el.com>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andi Kleen <ak@...ux.intel.com>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -v5] x86: MCE: Re-implement MCE log ring buffer as
	per-CPU ring buffer


* Huang Ying <ying.huang@...el.com> wrote:

> On Mon, 2009-06-08 at 15:38 +0800, Ingo Molnar wrote:
> > * Huang Ying <ying.huang@...el.com> wrote:
> > 
> > > On Mon, 2009-06-08 at 15:20 +0800, Ingo Molnar wrote:
> > > > * Huang Ying <ying.huang@...el.com> wrote:
> > > > 
> > > > > Re-implement MCE log ring buffer as per-CPU ring buffer for better 
> > > > > scalability.
> > > > 
> > > > this should be done using the generic ring-buffer code - see 
> > > > include/linux/ring_buffer.h. Having a private implementation in 
> > > > architecture code is not really acceptable.
> > > 
> > > MCE log ring buffer need to be NMI-safe, while current generic 
> > > ring-buffer code is not NMI safe. [...]
> > 
> > Then please work with Steve to make it NMI safe (or do so yourself) 
> > - i've Cc:-ed him - that way we help the core kernel: one of its 
> > essential facilities will get one more user. We dont put private, 
> > open-coded ring-buffer facilities into architecture code.
> 
> Steve have said he has a NMI-safe solution, but it is under patent 
> application. It seems that patent application will take very long 
> time, so we decide to enhance mce log buffer instead of waiting.

Nah - if patent applications held up releases of code and products 
up to the point where a patent issues then Intel wouldnt be able to 
release a new CPU for a decade or so ;-)

Anyway, i'll let Steve clarify the status of the NMI-safe ringbuffer 
patches.

	Ingo
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