linux-kernel - Re: [PATCH] x86_64: dynamic MCE poll interval

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Date:	Fri, 27 Apr 2007 09:58:14 -0700
From:	"Tim Hockin" <thockin@...gle.com>
To:	"Andi Kleen" <ak@....de>
Cc:	vojtech@...e.cz, linux-kernel@...r.kernel.org, akpm@...gle.com
Subject: Re: [PATCH] x86_64: dynamic MCE poll interval

On 27 Apr 2007 11:09:17 +0200, Andi Kleen <ak@....de> wrote:
> On Thu, Apr 26, 2007 at 06:02:52PM -0700, Tim Hockin wrote:
> > Description:
> >  This patch makes the MCE poller adjust the polling interval dynamically.
> >  If we find an MCE, poll 2x faster (down to 10 ms).  When we stop finding
> >  MCEs, poll 2x slower (up to check_interval seconds).  The check_interval
> >  tunable becomes the max polling interval.
>
> Can you please fix the documentation then?

Which documentation, specifically? :)

> > Result:
> >  If you start to take a lot of correctable errors (not exceptions), you
> >  log them faster and more accurately (less chance of overflowing the MCA
> >  registers).  If you don't take a lot of errors, you will see no change.
>
> Makes sense.
>
> AMD RevF can do this using the threshold interrupts too for DIMM errors
> too without any delays -- perhaps it would also make sense to configure
> this by default that it always triggers on all DIMM errors.
> Right now it is just an option in /sys

Can I look at this as a followon patch?  I have a number of mce
related patches in the pipeline, and I am trying to keep them small
for testing sanity - they are hard enough to test :)

> The printk should not happen too often. Can you add some hardcoded
> limit there than it doesn't happen more often than every hour or so
> (or perhaps use a exponential backoff here too?)
> It is only to tell users to check mcelog output.

Sure.  I'll fix it up and hit you again today.
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