linux-kernel - Re: [PATCH v24b] RAS: Add a tracepoint for reporting memory controller events

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Message-ID: <4FBB67ED.70606@redhat.com>
Date:	Tue, 22 May 2012 07:18:21 -0300
From:	Mauro Carvalho Chehab <mchehab@...hat.com>
To:	Borislav Petkov <borislav.petkov@....com>
CC:	"Luck, Tony" <tony.luck@...el.com>, Ingo Molnar <mingo@...nel.org>,
	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 v24b] RAS: Add a tracepoint for reporting memory controller
 events

Em 22-05-2012 06:28, Borislav Petkov escreveu:
> On Tue, May 22, 2012 at 12:04:48AM -0300, Mauro Carvalho Chehab wrote:
>> +TRACE_EVENT(mc_event,
>> +
>> +	TP_PROTO(const unsigned int err_type,
>> +		 const unsigned int mc_index,
>> +		 const char *error_msg,
>> +		 const char *label,
>> +		 int layer0,
>> +		 int layer1,
>> +		 int layer2,
> 
> Those are EDAC-internal layer representation, why are they exported to
> userspace? Userspace needs only the location and label AFAICT.

Those are not the EDAC internal layer representation. They're the physical
location of the DIMM or rank.

> If you export them to userspace, they need much more meaningful names -
> layer{0,1,2} mean nothing outside of the kernel.

Ok. Do you have a better naming suggestion?

What about layer0_pos, layer1_pos, layer2_pos?

> 
>> +		 unsigned long pfn,
>> +		 unsigned long offset,
>> +		 unsigned long grain,
> 
> Why aren't those a single 'unsigned long address' since they all are
> computed from it?

We can merge pfn and offset into "unsigned long address".

With regards to the grain, it is an address mask, written with a "short" way.
So, grain 32, for example, means:
	ffff:ffff:ffff:fffe0

As the current EDAC API exports it as grain, IMO, it is better to keep it as-is,
but it won't be hard to do:
	unsigned long mask = ((unsigned long) -1) && (1 - grain)

What do you think?

>> +		 unsigned long syndrome,
>> +		 const char *driver_detail),
>> +
>> +	TP_ARGS(err_type, mc_index, error_msg, label, layer0, layer1, layer2,
>> +		pfn, offset, grain, syndrome, driver_detail),
>>
>> The address is there using the edac way to represent it (page, offset, grain).
> 

Regards,
Mauro
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