linux-kernel - Re: [PATCH] RAS: Add a tracepoint for reporting memory controller events

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Message-ID: <4FC787BF.3020006@redhat.com>
Date:	Thu, 31 May 2012 12:01:19 -0300
From:	Mauro Carvalho Chehab <mchehab@...hat.com>
To:	Borislav Petkov <bp@...64.org>
CC:	"Luck, Tony" <tony.luck@...el.com>,
	Linux Edac Mailing List <linux-edac@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Aristeu Rozanski <arozansk@...hat.com>,
	Doug Thompson <norsk5@...oo.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH] RAS: Add a tracepoint for reporting memory controller
 events

Em 31-05-2012 11:54, Borislav Petkov escreveu:
> On Thu, May 31, 2012 at 11:44:58AM -0300, Mauro Carvalho Chehab wrote:
>> It doesn't matter if some drivers use statically-defined grain, while
>> others are dynamic: at the reported event, the grain should be there
>> for both types of drivers.
> 
> And only a small subset of the drivers _reportedly_ change grain
> frequently - the majority of them have a static, seldomly changing
> value. Which means, we don't fill up tracepoint records needlessly which
> seldomly changing values.

Grain is an error property, associated with the error address.
It is as simple as that. It is not a "change grain frequently" type
of thing: each address have its associated grain.

Ok, on _old_ hardware, this used to be constant, but on modern ones,
this is associated with the error type, as Tony already explained.

Don't create a crappy API, just because you want to save 32 bits.
Btw, a "string" grain will spare much more than just 32 bits.

Mauro.

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