From: Peter Zijlstra <peterz@infradead.org>
To: Borislav Petkov <borislav.petkov@amd.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Stephane Eranian <eranian@google.com>,
linux-kernel@vger.kernel.org, andi@firstfloor.org, mingo@elte.hu,
ming.m.lin@intel.com,
Andreas Herrmann <andreas.herrmann3@amd.com>,
Dimitri Sivanich <sivanich@sgi.com>,
Dmitry Adamushko <dmitry.adamushko@gmail.com>
Subject: Re: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge
Date: Fri, 08 Jun 2012 15:54:29 +0200 [thread overview]
Message-ID: <1339163669.2507.16.camel@laptop> (raw)
In-Reply-To: <20120608135117.GB31359@aftab.osrc.amd.com>
On Fri, 2012-06-08 at 15:51 +0200, Borislav Petkov wrote:
> Reportedly, there are some obscure systems which need different
> microcode versions per CPU:
>
> http://lkml.indiana.edu/hypermail/linux/kernel/1105.3/01010.html
*groan*,.. ok.
> > The biggest problem is finding when the minimum revision changes, at
> > best this is a n log n sorting problem due to the per-cpu setup, but I
> > couldn't be arsed to implement a tree or anything fancy since it all
> > stinks anyway.
>
> I know. Can't you just iterate over all CPUs and collect the lowest
> ucode version? Provided, of course, newer microcode versions means a
> higher version number.
That's what I do.. but that's O(n) per cpu, so if you update all cpus,
that's O(n^2).
You don't know when userspace is done updating the 'last' cpu, so you
have to scan all cpus for every cpu.
I'm sure the SGI people with their silly CPU counts aren't too thrilled
to have this.
next prev parent reply other threads:[~2012-06-08 13:54 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-07 7:15 [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge Stephane Eranian
2012-06-07 10:18 ` Peter Zijlstra
2012-06-07 10:35 ` Stephane Eranian
2012-06-07 10:45 ` Peter Zijlstra
2012-06-07 10:48 ` Stephane Eranian
2012-06-07 11:15 ` Peter Zijlstra
2012-06-08 9:35 ` Ingo Molnar
2012-06-08 10:00 ` Peter Zijlstra
2012-06-08 10:03 ` Stephane Eranian
2012-06-08 13:26 ` Peter Zijlstra
2012-06-08 13:51 ` Borislav Petkov
2012-06-08 13:54 ` Peter Zijlstra [this message]
2012-06-08 14:15 ` Borislav Petkov
2012-06-08 14:20 ` Peter Zijlstra
2012-06-08 14:36 ` Borislav Petkov
2012-06-08 14:45 ` Peter Zijlstra
2012-06-08 15:09 ` Borislav Petkov
2012-06-08 13:56 ` Peter Zijlstra
2012-06-08 14:03 ` Borislav Petkov
2012-06-08 13:59 ` Peter Zijlstra
2012-06-08 14:03 ` Stephane Eranian
2012-06-08 14:17 ` Borislav Petkov
2012-06-08 16:02 ` H. Peter Anvin
2012-06-08 21:02 ` Henrique de Moraes Holschuh
2012-06-08 21:16 ` Borislav Petkov
2012-06-08 14:07 ` Stephane Eranian
2012-06-08 14:13 ` Peter Zijlstra
2012-06-08 14:19 ` Borislav Petkov
2012-06-08 14:23 ` Peter Zijlstra
2012-06-08 14:26 ` Stephane Eranian
2012-06-08 14:25 ` Peter Zijlstra
2012-06-08 14:26 ` Stephane Eranian
2012-06-12 8:14 ` Stephane Eranian
2012-06-08 16:28 ` Stephane Eranian
2012-06-08 18:49 ` Peter Zijlstra
2012-06-08 16:50 ` Andi Kleen
2012-06-08 18:05 ` Borislav Petkov
2012-06-08 18:52 ` Peter Zijlstra
2012-06-08 20:38 ` Borislav Petkov
2012-06-12 17:07 ` Robert Richter
2012-06-12 17:09 ` Stephane Eranian
2012-06-12 17:13 ` Peter Zijlstra
2012-06-12 17:17 ` Borislav Petkov
2012-06-12 17:18 ` Peter Zijlstra
2012-06-12 17:23 ` Borislav Petkov
2012-06-12 17:26 ` Peter Zijlstra
2012-06-12 17:35 ` Borislav Petkov
2012-06-12 17:40 ` Peter Zijlstra
2012-06-12 18:04 ` Andi Kleen
2012-06-12 20:10 ` Borislav Petkov
2012-06-13 1:04 ` Henrique de Moraes Holschuh
2012-06-13 6:51 ` Borislav Petkov
2012-06-13 12:36 ` Henrique de Moraes Holschuh
2012-06-13 16:11 ` Borislav Petkov
2012-06-13 21:41 ` Henrique de Moraes Holschuh
2012-06-15 12:37 ` Borislav Petkov
2012-06-15 12:42 ` Peter Zijlstra
2012-06-15 12:52 ` Borislav Petkov
2012-06-15 16:52 ` [PATCH] x86, microcode: Make reload interface per system Borislav Petkov
2012-06-15 17:16 ` Peter Zijlstra
2012-06-15 17:49 ` Borislav Petkov
2012-06-19 2:46 ` Henrique de Moraes Holschuh
2012-06-19 3:31 ` H. Peter Anvin
2012-06-19 5:11 ` Borislav Petkov
2012-06-19 8:17 ` Peter Zijlstra
2012-06-19 10:22 ` Borislav Petkov
2012-06-19 10:26 ` Peter Zijlstra
2012-06-19 15:06 ` Borislav Petkov
2012-06-19 15:57 ` H. Peter Anvin
2012-06-19 18:22 ` Henrique de Moraes Holschuh
2012-06-19 20:22 ` H. Peter Anvin
2012-06-20 23:46 ` Henrique de Moraes Holschuh
2012-06-20 23:49 ` H. Peter Anvin
2012-06-21 0:06 ` Henrique de Moraes Holschuh
2012-06-21 0:18 ` H. Peter Anvin
2012-06-21 2:33 ` Henrique de Moraes Holschuh
2012-06-19 5:03 ` Borislav Petkov
2012-06-19 18:57 ` Henrique de Moraes Holschuh
2012-06-19 22:19 ` Borislav Petkov
2012-06-19 2:42 ` [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge Henrique de Moraes Holschuh
2012-06-12 17:23 ` Robert Richter
2012-06-12 17:15 ` Borislav Petkov
2012-06-07 13:28 ` Andi Kleen
2012-06-07 13:27 ` Andi Kleen
2012-06-12 18:35 ` H. Peter Anvin
2012-06-12 19:07 ` Borislav Petkov
2012-06-12 19:33 ` Peter Zijlstra
2012-06-12 19:35 ` Andi Kleen
2012-06-12 19:49 ` Borislav Petkov
2012-06-12 20:28 ` H. Peter Anvin
2012-06-12 20:37 ` Borislav Petkov
2012-06-12 20:42 ` H. Peter Anvin
2012-06-12 20:56 ` Borislav Petkov
2012-06-12 20:58 ` H. Peter Anvin
2012-06-12 21:04 ` Borislav Petkov
2012-06-13 8:38 ` Peter Zijlstra
2012-06-13 14:00 ` H. Peter Anvin
2012-06-13 15:37 ` Peter Zijlstra
2012-06-13 15:46 ` H. Peter Anvin
2012-06-13 12:39 ` Peter Zijlstra
2012-06-13 13:22 ` H. Peter Anvin
2012-06-13 14:01 ` Henrique de Moraes Holschuh
2012-06-13 8:32 ` Peter Zijlstra
2012-06-13 13:59 ` H. Peter Anvin
2012-06-13 15:32 ` Peter Zijlstra
2012-06-13 15:38 ` H. Peter Anvin
2012-06-12 20:27 ` H. Peter Anvin
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