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Date: Thu, 2 Jan 2025 21:36:25 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
	linux-kbuild@vger.kernel.org, bpf <bpf@vger.kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
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	Martin Kelly <martin.kelly@crowdstrike.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH 14/14] scripts/sorttable: ftrace: Do not add weak
 functions to available_filter_functions
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On Thu, Jan 02, 2025 at 03:30:16PM -0500, Steven Rostedt wrote:
> On Thu, 2 Jan 2025 21:24:04 +0100
> Peter Zijlstra <peterz@infradead.org> wrote:
> 
> > It is not. If kallsyms is fixed, you can use that to tell which
> > fentry/mcount sites are 'invalid'.
> 
> I can't use kallsyms for valid tests at boot up. Even with a binary search,
> it's still rather slow. The ftrace table is created at early boot, even
> before scheduling (it's needed before you can enable boot time function
> tracing), so any slow down in creating that table slows down the boot, and
> people will notice.

I'm not sure I understand, up until you've started userspace, nobody
cares about those weird indexes.