From: Steven Rostedt <rostedt@goodmis.org>
To: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Phil Auld <pauld@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Kate Carcia <kcarcia@redhat.com>,
Jonathan Corbet <corbet@lwn.net>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Clark Willaims <williams@redhat.com>,
John Kacur <jkacur@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH V4 05/12] trace/hwlat: Support hotplug operations
Date: Mon, 21 Jun 2021 11:25:28 -0400 [thread overview]
Message-ID: <20210621112528.12aee665@oasis.local.home> (raw)
In-Reply-To: <c4b86b0e-b45d-3039-f49c-0dc53e1adcbd@redhat.com>
On Mon, 21 Jun 2021 13:34:44 +0200
Daniel Bristot de Oliveira <bristot@redhat.com> wrote:
> > And of course, because get_online_cpus() is called within
> > trace_types_lock, doing this check is going to cause a lock inversion.
> >
>
> Yep! I tried to take the trace_type_lock here, and got the lockdep info about
> this problem.
>
> > The only thing I could think of is to wake up a worker thread to do the
> > work. That is, this just wakes the worker thread, then the worker grabs
> > the trace_types_lock, iterates through the cpu mask of expect running
> > threads, and then starts or kills them depending on the hwlat_busy
> > value.
>
> So, it will not wait for the kworker to run?
What wont wait?
-- Steve
next prev parent reply other threads:[~2021-06-21 15:25 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 9:28 [PATCH V4 00/12] hwlat improvements and osnoise/timerlat tracers Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 01/12] trace/hwlat: Fix Clark's email Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 02/12] trace/hwlat: Implement the mode config option Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 03/12] trace/hwlat: Switch disable_migrate to mode none Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 04/12] trace/hwlat: Implement the per-cpu mode Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 05/12] trace/hwlat: Support hotplug operations Daniel Bristot de Oliveira
2021-06-18 16:45 ` Steven Rostedt
2021-06-18 19:00 ` Steven Rostedt
2021-06-21 11:34 ` Daniel Bristot de Oliveira
2021-06-21 15:25 ` Steven Rostedt [this message]
2021-06-21 16:14 ` Daniel Bristot de Oliveira
2021-06-21 17:46 ` Steven Rostedt
2021-06-22 14:05 ` Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 06/12] trace: Add a generic function to read/write u64 values from tracefs Daniel Bristot de Oliveira
2021-06-18 16:56 ` Steven Rostedt
2021-06-21 11:50 ` Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 07/12] trace/hwlat: Use trace_min_max_param for width and window params Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 08/12] trace/hwlat: Remove printk from sampling loop Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 09/12] trace: Add __print_ns_to_secs() and __print_ns_without_secs() helpers Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 10/12] trace: Add osnoise tracer Daniel Bristot de Oliveira
2021-06-18 17:55 ` Steven Rostedt
2021-06-21 12:09 ` Daniel Bristot de Oliveira
2021-06-18 18:27 ` Steven Rostedt
2021-06-21 12:09 ` Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 11/12] trace: Add timerlat tracer Daniel Bristot de Oliveira
2021-06-15 9:28 ` [PATCH V4 12/12] trace/osnoise: Support hotplug operations Daniel Bristot de Oliveira
2021-06-18 19:04 ` Steven Rostedt
2021-06-21 12:18 ` Daniel Bristot de Oliveira
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