linux-kernel - Re: [PATCH v2] arm64: Disable branch profiling for all arm64 code

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Message-ID: <20260106111142.1c123f12@gandalf.local.home>
Date: Tue, 6 Jan 2026 11:11:42 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Mark Rutland <mark.rutland@....com>
Cc: Breno Leitao <leitao@...ian.org>, Catalin Marinas
 <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Laura Abbott
 <labbott@...hat.com>, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, Masami
 Hiramatsu <mhiramat@...nel.org>, kernel-team@...a.com, puranjay@...nel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH v2] arm64: Disable branch profiling for all arm64 code

On Tue, 6 Jan 2026 12:24:09 +0000
Mark Rutland <mark.rutland@....com> wrote:

> Whoops; s/CONFIG_DEBUG_VIRTUAL/PROFILE_ANNOTATED_BRANCHES/ in both
> places in my reply.

Note, it could still be useful ;-) 

I've been running my yearly branch profiling build on both my main
workstation and my server. I post the results from my server publicly (this
is updated every night):

   https://rostedt.org/branches/current

If you check out the branch_annotated file, you can see there's still quite
a bit that gets it wrong. Some of these is because of bad assumptions by
the developer, others is because the code moved around causing new branches
to make later annotated branches go the opposite way.

Note, its still slow to download, not only because my internet is 20mbs up,
but also because that web server is running on a machine with this
profiling still enabled. I'll rebuild the kernel and disable it this weekend.

-- Steve