linux-kernel - Re: [PATCH] x86, mce: short output of MCE banks ownership information

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Message-ID: <4AE951F4.7080406@jp.fujitsu.com>
Date:	Thu, 29 Oct 2009 17:27:32 +0900
From:	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Roland Dreier <rdreier@...co.com>, linux-kernel@...r.kernel.org,
	x86@...nel.org, Andi Kleen <ak@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Mike Travis <travis@....com>
Subject: Re: [PATCH] x86, mce: short output of MCE banks ownership	information

Ingo Molnar wrote:
> * Hidetoshi Seto <seto.hidetoshi@...fujitsu.com> wrote:
>> Maybe there would be more desirable ways, but I think that "compress 
>> messages shorter to bear heavy repeating" will be a good way at this 
>> time.
> 
> We really want to only print out relevant information. 128 lines of 
> identical output is not relevant. (or 2x 64 lines, or 4096 lines of 
> identical output)
> 
> So we only want to print MCE setup messages on the boot CPU. That gives 
> us 90% of the benefits already: we see the rough structure of the 
> hardware, and if the bootup has a problem with MCE initialization we get 
> relevant printouts that helps debugging.
> 
> Now, it's certainly true that with things like MCE bank sharing the MCE 
> setup output from different CPUs might not be identical all the time - 
> but the information is represented in other (topology) info anyway. (and 
> if not it wasnt all that important to begin with)
> 
> For non-boot CPUs we can perhaps add a mce=verbose (default-disabled) 
> mode of bootup that allows all CPUs to be printed - should there be any 
> problem with MCE details only visible on non-boot CPUs. (unlikely)

How about having a kind of "boot=quiet_ap" which suppress boot-time messages
for all non-boot CPUs, rather than "mce=verbose" which only suppress one
(or, with thermal message, two) line?  I don't not understand why this problem
would be solved only by removing the lines from mce subsystem.

I have no problem on my box with 16 CPUs, but I would not think so if there
were 128 or 4096.  Then I'd like to see in short:
  :
 2048 CPUs available, 4096 CPUs total
 Booting 2047 processors ........<snip>..... OK.
 Total of 2048 processors activated (XXXXXXXXXXX.XX BogoMIPS).
  :

Anyway this will be a quite trivial problem for desktop/notebook users.


Thanks,
H.Seto

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