From: Steven Rostedt <rostedt@goodmis.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux trace kernel <linux-trace-kernel@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, Masami Hiramatsu <mhiramat@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast
Date: Fri, 9 Jan 2026 17:00:28 -0500 [thread overview]
Message-ID: <20260109170028.0068a14d@fedora> (raw)
In-Reply-To: <CAADnVQLeCLRhx1Oe5DdJCT0e+WWq4L3Rdee1Ky0JNNh3LdozeQ@mail.gmail.com>
On Fri, 9 Jan 2026 13:54:34 -0800
Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
> On Fri, Jan 9, 2026 at 12:21 PM Mathieu Desnoyers
> <mathieu.desnoyers@efficios.com> wrote:
> >
> >
> > * preempt disable/enable pair: 1.1 ns
> > * srcu-fast lock/unlock: 1.5 ns
> >
> > CONFIG_RCU_REF_SCALE_TEST=y
> > * migrate disable/enable pair: 3.0 ns
>
> .. and you're arguing that 3ns vs 1ns difference is so important
> for your out-of-tree tracer that in-tree tracers need to do
> some workarounds?! wtf
This has nothing to do with out of tree tracers. The overhead of the
22ns is for any tracepoint in an in-tree module. That's because the
rq->nr_pinned isn't exported for modules to use.
-- Steve
next prev parent reply other threads:[~2026-01-09 22:00 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-09 3:05 [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast Steven Rostedt
2026-01-09 14:40 ` Mathieu Desnoyers
2026-01-09 17:21 ` Steven Rostedt
2026-01-09 18:58 ` Mathieu Desnoyers
2026-01-13 13:56 ` Sebastian Andrzej Siewior
2026-01-09 19:10 ` Alexei Starovoitov
2026-01-09 19:19 ` Steven Rostedt
2026-01-09 20:21 ` Mathieu Desnoyers
2026-01-09 21:02 ` Steven Rostedt
2026-01-12 7:23 ` Menglong Dong
2026-01-12 15:31 ` Peter Zijlstra
2026-01-12 15:36 ` Steven Rostedt
2026-01-12 15:44 ` Peter Zijlstra
2026-01-09 21:54 ` Alexei Starovoitov
2026-01-09 22:00 ` Steven Rostedt [this message]
2026-01-09 22:18 ` Alexei Starovoitov
2026-01-09 22:31 ` Mathieu Desnoyers
2026-01-09 22:33 ` Steven Rostedt
2026-01-09 22:39 ` Steven Rostedt
2026-01-10 0:35 ` Alexei Starovoitov
2026-01-10 16:14 ` Steven Rostedt
2026-01-11 20:04 ` Alexei Starovoitov
2026-01-11 22:09 ` Steven Rostedt
2026-01-11 23:38 ` Alexei Starovoitov
2026-01-12 13:53 ` Steven Rostedt
2026-01-12 17:19 ` Alexei Starovoitov
2026-01-13 14:23 ` Sebastian Andrzej Siewior
2026-01-13 23:44 ` Alexei Starovoitov
2026-01-09 19:19 ` Yonghong Song
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