From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Wander Lairson Costa <wander@redhat.com>,
linux-trace-kernel@vger.kernel.org,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] ftrace: Correct preemption accounting for function tracing.
Date: Fri, 21 Feb 2025 17:21:46 +0100 [thread overview]
Message-ID: <20250221162146.9KWeIdA0@linutronix.de> (raw)
In-Reply-To: <20250220115400.4d75d881@gandalf.local.home>
On 2025-02-20 11:54:00 [-0500], Steven Rostedt wrote:
> > kworker/0:5-88 [000] D.Zf2 211.983391: igbvf_reset_L14: (igbvf_reset+0x62/0x120 [igbvf])
> > kworker/0:5-88 [000] .N... 211.983396: igbvf_reset_L16: (igbvf_reset+0x7b/0x120 [igbvf])
…
> > (Except in line 6 where it show 'f', which seems to be an unrelated issue)
>
> But it appears to be consistent.
>
> Let me go and add some probes and see what they show. The output you gave
> me that I requested didn't show anything unusual.
Since I just noticed that you posted the patches, did you find anything?
From looking at it, if we preemption at 0, migrate disable at 3 then a
substraction of one would underflow the preemption counter to f and
migrate disable to 2. But based on code inspection mg should be at 1.
And this does not explain where D & Z is coming from.
> -- Steve
Sebastian
next prev parent reply other threads:[~2025-02-21 16:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-20 14:07 [PATCH] ftrace: Correct preemption accounting for function tracing Sebastian Andrzej Siewior
2025-02-20 15:10 ` Wander Lairson Costa
2025-02-20 16:54 ` Steven Rostedt
2025-02-21 16:21 ` Sebastian Andrzej Siewior [this message]
2025-02-21 16:48 ` Steven Rostedt
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