linux-kernel - Re: [PATCH 00/10] perf/uprobe: Optimize uprobes

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Message-ID: <20240709101634.GJ27299@noisy.programming.kicks-ass.net>
Date: Tue, 9 Jul 2024 12:16:34 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Jiri Olsa <olsajiri@...il.com>
Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>,
	Masami Hiramatsu <mhiramat@...nel.org>, mingo@...nel.org,
	andrii@...nel.org, linux-kernel@...r.kernel.org,
	rostedt@...dmis.org, oleg@...hat.com, clm@...a.com,
	paulmck@...nel.org, bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH 00/10] perf/uprobe: Optimize uprobes

On Tue, Jul 09, 2024 at 12:01:03PM +0200, Jiri Olsa wrote:
> On Tue, Jul 09, 2024 at 11:03:04AM +0200, Peter Zijlstra wrote:
> > On Mon, Jul 08, 2024 at 05:25:14PM -0700, Andrii Nakryiko wrote:
> > 
> > > Ramping this up to 16 threads shows that mmap_rwsem is getting more
> > > costly, up to 45% of CPU. SRCU is also growing a bit slower to 19% of
> > > CPU. Is this expected? (I'm not familiar with the implementation
> > > details)
> > 
> > SRCU getting more expensive is a bit unexpected, it's just a per-cpu
> > inc/dec and a full barrier.
> > 
> > > P.S. Would you be able to rebase your patches on top of latest
> > > probes/for-next, which include Jiri's sys_uretprobe changes. Right now
> > > uretprobe benchmarks are quite unrepresentative because of that.
> > 
> > What branch is that? kernel/events/ stuff usually goes through tip, no?
> 
> it went through the trace tree:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git probes/for-next
> 
> and it's in linux-next/master already

FFS :-/ That touches all sorts and doesn't have any perf ack on. Masami
what gives?