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Re: [Patch V1 1/3] x86, mce: MCE log size not enough for high core parts

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On Thu, Sep 24, 2015 at 01:48:38AM -0400, Ashok Raj wrote:
> MCE_LOG_LEN appears to be short for high core count parts. Especially when
> handling fatal errors, we don't clear MCE banks. Socket level MC banks
> are visible to all CPUs that share banks.
> 
> Assuming 18 core part, 2 threads per core 2 banks per thread and couple uncore
> MSRs. Rounding to 128 with some fudge to grow in future.
> 
> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> Suggested-by: Tony Luck <tony.luck@intel.com>
> ---
>  arch/x86/include/asm/mce.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
> index 2dbc0bf..4293ae7 100644
> --- a/arch/x86/include/asm/mce.h
> +++ b/arch/x86/include/asm/mce.h
> @@ -88,7 +88,7 @@
>  #define MCE_EXTENDED_BANK	128
>  #define MCE_THERMAL_BANK	(MCE_EXTENDED_BANK + 0)
>  
> -#define MCE_LOG_LEN 32
> +#define MCE_LOG_LEN 		128
>  #define MCE_LOG_SIGNATURE	"MACHINECHECK"

Hmm, I don't think this is what I meant when we talked about it
previously. So let me try again:

Now that we have this shiny 2-pages sized lockless gen_pool, why are we
still dealing with struct mce_log mcelog? Why can't we rip it out and
kill it finally? And switch to the gen_pool?

All code that reads from mcelog - /dev/mcelog chrdev - should switch to
the lockless buffer and will iterate through the logged MCEs there.

I think this way we're much better prepared for future machine sizes.
We can even use memblock to allocate appropriate memory at boot for the
gen_pool if the 2 pages are not enough.

Hmmm?

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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[Patch V1 1/3] x86, mce: MCE log size not enough for high core parts Ashok Raj <ashok.raj@intel.com> - 2015-09-24 07:00 +0200
  [Patch V1 2/3] x86, mce: Refactor parts of mce_log() to reuse when logging from offline CPUs Ashok Raj <ashok.raj@intel.com> - 2015-09-24 07:00 +0200
  Re: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts Borislav Petkov <bp@alien8.de> - 2015-09-24 17:50 +0200
    RE: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts "Luck, Tony" <tony.luck@intel.com> - 2015-09-24 20:50 +0200
      Re: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts Borislav Petkov <bp@alien8.de> - 2015-09-24 21:00 +0200
        RE: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts "Luck, Tony" <tony.luck@intel.com> - 2015-09-24 21:10 +0200
          Re: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts Borislav Petkov <bp@alien8.de> - 2015-09-24 21:30 +0200
            Re: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts "Raj, Ashok" <ashok.raj@intel.com> - 2015-09-24 22:30 +0200
              Re: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts Borislav Petkov <bp@alien8.de> - 2015-09-24 23:10 +0200
                Re: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts "Raj, Ashok" <ashok.raj@intel.com> - 2015-09-24 23:30 +0200
                Re: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts Borislav Petkov <bp@alien8.de> - 2015-09-25 10:30 +0200
                Re: [Patch V1 1/3] x86, mce: MCE log size not enough for high core  parts "Raj, Ashok" <ashok.raj@intel.com> - 2015-09-25 18:30 +0200

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