All of lore.kernel.org
 help / color / mirror / Atom feed
From: Viktor Rosendahl <viktor.rosendahl@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Joel Fernandes <joel@joelfernandes.org>
Cc: paulmck@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org
Subject: Re: [PATCH v5 1/4] ftrace: Implement fs notification for tracing_max_latency
Date: Wed, 4 Sep 2019 20:17:18 +0200	[thread overview]
Message-ID: <5bd4f538-f205-1134-d491-5a8727855b51@gmail.com> (raw)
In-Reply-To: <20190904081919.GA2349@hirez.programming.kicks-ass.net>

On 9/4/19 10:19 AM, Peter Zijlstra wrote:

>>
>> Adding Paul since RCU faces similar situations, i.e. raising softirq risks
>> scheduler deadlock in rcu_read_unlock_special() -- but RCU's solution is to
>> avoid raising the softirq and instead use irq_work.
> 
> Which is right.
> 

Thanks Joel and Peter for suggesting the irq_work facility.

I was ignorant of the existence of this facility.

It looks like it is the Holy Grail of deferred work, for this particular 
type of problem :)

It looks like it will be possible to both avoid deadlock and also avoid 
the ugly additions to the sched and idle code. In addition, the rest of 
the code will become a lot simpler.

best regards,

Viktor

  parent reply	other threads:[~2019-09-04 18:17 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-03 13:25 [PATCH v5 0/4] Some new features for the preempt/irqsoff tracers Viktor Rosendahl
2019-09-03 13:25 ` [PATCH v5 1/4] ftrace: Implement fs notification for tracing_max_latency Viktor Rosendahl
2019-09-04  4:00   ` Joel Fernandes
2019-09-04  8:19     ` Peter Zijlstra
2019-09-04 13:42       ` Joel Fernandes
2019-09-04 18:17       ` Viktor Rosendahl [this message]
2019-09-04 10:21     ` Paul E. McKenney
2019-09-04  8:20   ` Peter Zijlstra
2019-09-04 11:37     ` Steven Rostedt
2019-09-04 11:39   ` Steven Rostedt
2019-09-04 19:00     ` Viktor Rosendahl
2019-09-03 13:26 ` [PATCH v5 2/4] preemptirq_delay_test: Add the burst feature and a sysfs trigger Viktor Rosendahl
2019-09-04 11:42   ` Steven Rostedt
2019-09-04 19:10     ` Viktor Rosendahl
2019-09-05 16:52       ` Steven Rostedt
2019-09-05 18:27         ` Viktor Rosendahl
2019-09-03 13:26 ` [PATCH v5 3/4] Add the latency-collector to tools Viktor Rosendahl
2019-09-03 13:26 ` [PATCH v5 4/4] ftrace: Add an option for tracing console latencies Viktor Rosendahl
2019-09-04  5:02   ` kbuild test robot

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=5bd4f538-f205-1134-d491-5a8727855b51@gmail.com \
    --to=viktor.rosendahl@gmail.com \
    --cc=joel@joelfernandes.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rt-users@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=paulmck@kernel.org \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.