From: Thomas Gleixner <tglx@linutronix.de>
To: Prasad Sodagudi <psodagud@codeaurora.org>,
rostedt@goodmis.org, qais.yousef@arm.com, peterz@infradead.org,
mingo@kernel.org, cai@lca.pw, tyhicks@canonical.com,
arnd@arndb.de
Cc: rameezmustafa@codeaurora.org, linux-kernel@vger.kernel.org,
Prasad Sodagudi <psodagud@codeaurora.org>
Subject: Re: [PATCH 1/2] cpu/hotplug: Add cpuhp_latency trace event
Date: Mon, 28 Sep 2020 16:58:09 +0200 [thread overview]
Message-ID: <87tuvij6da.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <1600904266-102397-2-git-send-email-psodagud@codeaurora.org>
On Wed, Sep 23 2020 at 16:37, Prasad Sodagudi wrote:
> Add ftrace event trace_cpuhp_latency to track cpu
> hotplug latency. It helps to track the hotplug latency
> impact by firmware changes and kernel cpu hotplug callbacks.
Why?
And even if that makes sense, the implementation makes absolutely no
sense at all.
trace_cpuhp_callback_enter();
callback();
trace_cpuhp_callback_exit();
No point in all this start time and conditional sched_clock() muck.
But then again, hotplug is slow by definition and nobody cares.
Thanks,
tglx
next prev parent reply other threads:[~2020-09-28 14:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-23 23:37 [PATCH 0/2] measure latency of cpu hotplug path Prasad Sodagudi
2020-09-23 23:37 ` [PATCH 1/2] cpu/hotplug: Add cpuhp_latency trace event Prasad Sodagudi
2020-09-28 14:58 ` Thomas Gleixner [this message]
2020-09-23 23:37 ` [PATCH 2/2] cpu-hotplug: Always use real time scheduling when hotplugging a CPU Prasad Sodagudi
2020-09-24 8:34 ` [PATCH 0/2] measure latency of cpu hotplug path peterz
2020-09-24 14:58 ` Steven Rostedt
2020-09-28 2:41 ` psodagud
2020-09-28 7:40 ` Peter Zijlstra
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