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Re: [PATCH] x86, perf, bts: disable BTS from Nehalem to Ivy Bridge
- From: Ingo Molnar <mingo at kernel dot org>
- To: markus dot t dot metzger at intel dot com
- Cc: mingo at redhat dot com, mingo at elte dot hu, linux-kernel at vger dot kernel dot org, Mark Kettenis <kettenis at gnu dot org>, Pedro Alves <palves at redhat dot com>, Jan Kratochvil <jan dot kratochvil at redhat dot com>, gdb-patches at sourceware dot org
- Date: Thu, 24 Jan 2013 16:46:37 +0100
- Subject: Re: [PATCH] x86, perf, bts: disable BTS from Nehalem to Ivy Bridge
- References: <1354876511-25294-1-git-send-email-markus.t.metzger@intel.com>
* markus.t.metzger@intel.com <markus.t.metzger@intel.com> wrote:
> From: Markus Metzger <markus.t.metzger@intel.com>
>
> Starting with Nehalem, the BTS "from" information may in some cases be
> incorrect (AAJ122).
>
> This has been detected while adding branch tracing support to gdb, where it
> results in sporadic test fails.
>
> Disable BTS support on Nehalem, Westmere, Sandy Bridge, and Ivy Bridge.
But the failures are rare, so the BTS data is still correct
statistically, by and large, right? So why not just keep it
as-is and teach tooling to be more robust about implausible
trace entries? It has to be ready for that eventuality *anyway*.
Thanks,
Ingo