From: Roland Dreier <rdreier@cisco.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>,
       Mike Travis <travis@sgi.com>, Thomas Gleixner <tglx@linutronix.de>,
       Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
       linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH] x86, mce: disable MCE if cpu has no MCE banks
References: <adaeip473qt.fsf@cisco.com> <4AE74D25.8090901@sgi.com>
	<4AE75DB9.3040702@sgi.com> <4AE7C396.7040109@jp.fujitsu.com>
	<4AE7D59D.9070307@linux.intel.com> <4AE7E40F.20602@jp.fujitsu.com>
	<4AE7E931.6040703@linux.intel.com>
Date: Wed, 28 Oct 2009 10:12:47 -0700
In-Reply-To: <4AE7E931.6040703@linux.intel.com> (Andi Kleen's message of "Wed,
	28 Oct 2009 07:48:17 +0100")
Message-ID: <ada8wevtpbk.fsf@cisco.com>
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.91 (gnu/linux)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1613
Lines: 39


 > Perhaps they could be also compressed a bit like SRAT.

Seems like a good idea... but I wonder what the best way to represent
things is.  For example I have a 2-socket Nehalem system that shows:

 2 times:  MCA banks CMCI:2 CMCI:3 CMCI:5 CMCI:6 SHD:8
 6 times:  MCA banks CMCI:2 CMCI:3 CMCI:5 SHD:6 SHD:8
 8 times:  MCA banks SHD:2 SHD:3 SHD:5 SHD:6 SHD:8

presumably the first line is once per package, the next line is for the
first sibling in all the other cores in a package, and the last line is
for the SMT siblings of all the cores.

But would we want to accumulate all the different combinations of banks
along with a CPU mask and then print something like:

 CPUs 0 4: MCA banks CMCI:2 CMCI:3 CMCI:5 CMCI:6 SHD:8
 CPUs 1 2 3 5 6 7: MCA banks CMCI:2 CMCI:3 CMCI:5 SHD:6 SHD:8
 CPUs 8 9 10 11 12 13 14 15: MCA banks SHD:2 SHD:3 SHD:5 SHD:6 SHD:8

of course output like that is going to lead to super-long lines on a
64-thread system.

Also I'm not sure of a clean way to implement this; unlike the SRAT
stuff, we need to deal with CPU hotplug so all this at best could be
__cpuinitdata, ie we can't discard it in most configs.

However the "MCA banks" output definitely is annoying on a 64-thread
system -- the amount of output is far greater than the utility of said
output.  So ideas on the best way to reduce this would be appreciated.

Thanks,
  Roland
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/