linux-kernel - Re: [PATCH v2 0/2] Update mce

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Date: Fri, 26 Jan 2024 11:27:21 +0100
From: Borislav Petkov <bp@...en8.de>
To: "Luck, Tony" <tony.luck@...el.com>
Cc: Avadhut Naik <avadhut.naik@....com>,
	"linux-trace-kernel@...r.kernel.org" <linux-trace-kernel@...r.kernel.org>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"yazen.ghannam@....com" <yazen.ghannam@....com>,
	"avadnaik@....com" <avadnaik@....com>
Subject: Re: [PATCH v2 0/2] Update mce_record tracepoint

On Thu, Jan 25, 2024 at 07:19:22PM +0000, Luck, Tony wrote:
> 8 bytes for PPIN, 4 more for microcode.

I know, nothing leads to bloat like 0.01% here, 0.001% there...

> Number of recoverable machine checks per system .... I hope the
> monthly rate should be countable on my fingers...

That's not the point. Rather, when you look at MCE reports, you pretty
much almost always go and collect additional information from the target
machine because you want to figure out what exactly is going on.

So what's stopping you from collecting all that static information
instead of parrotting it through the tracepoint with each error?

> PPIN is useful when talking to the CPU vendor about patterns of
> similar errors seen across a cluster.

I guess that is perhaps the only thing of the two that makes some sense
at least - the identifier uniquely describes which CPU the error comes
from...

> MICROCODE - gives a fast path to root cause problems that have already
> been fixed in a microcode update.

But that, nah. See above.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette