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Message-Id: <1432786398-23861-1-git-send-email-andi@firstfloor.org>
Date: Wed, 27 May 2015 21:13:13 -0700
From: Andi Kleen <andi@...stfloor.org>
To: peterz@...radead.org
Cc: acme@...nel.org, linux-kernel@...r.kernel.org, jolsa@...hat.com,
eranian@...gle.com
Subject:
[Repost; I forgot to copy linux-kernel earlier. Apologies if you
see it twice.]
Skylake moved to 32 Last Branch Records, from previously 16.
The current call stack LBR implementation reads all LBRs and
also saves/restores them on context switch. This patchkit
adds some optimizations to avoid extra costs in most cases
from the larger number of LBRs for call-stack, unless a nesting
larger than 16 is actually needed. It applies on top of the
earlier Skylake code. Some of the optimization will also benefit
earlier CPUs, such as Haswell.
note: one patch is for perf user space, the rest is kernel.
-Andi
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