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From: Peter Zijlstra <peterz@infradead.org>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Ivan Babrou <ibobrik@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>, Paul Turner <pjt@google.com>,
	Mike Galbraith <efault@gmx.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH 3/3] sched/fair: add tracepoints for cfs throttle
Date: Thu, 24 May 2018 09:11:52 +0200	[thread overview]
Message-ID: <20180524071152.GB12198@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAM_iQpUEvWrMPWQussA31kEAiutLR4WUVOtsohHm5hg4wt59Hw@mail.gmail.com>

On Wed, May 23, 2018 at 09:40:47PM -0700, Cong Wang wrote:
> On Wed, May 23, 2018 at 2:09 AM, Peter Zijlstra <peterz@infradead.org> wrote:

> > Yeah, don't worry. I hate tracepoints, I regret the existing ones, no
> > new ones will happen.
> 
> No matter you hate them or not, they are useful:

No argument there.

> Unlike in sched, tracepoints are welcome in networking:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/include/trace/events/tcp.h

They are also absolutely disallowed in the vfs..

> I don't want to change your mind, just want to show the facts.

The problem with tracepoints is that they can become ABI and you cannot
change them without breaking tools. This is a crap situation and I'm fed
up with it.

  reply	other threads:[~2018-05-24  7:12 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-22  6:20 [PATCH 0/3] sched/fair: improve CFS throttle Cong Wang
2018-05-22  6:20 ` [PATCH 1/3] sched/fair: make CFS bandwidth slice per cpu group Cong Wang
2018-05-22  6:20 ` [PATCH 2/3] sched/fair: accumulate unused cpu time for CFS throttle Cong Wang
2018-05-22  6:20 ` [PATCH 3/3] sched/fair: add tracepoints for cfs throttle Cong Wang
     [not found]   ` <CANWdNRCQCteO7L+Of7T2vWBW7GbMHyvyF5aSQMVYNGg_afxNhg@mail.gmail.com>
2018-05-23  0:34     ` Cong Wang
2018-05-23  9:09     ` Peter Zijlstra
2018-05-24  4:40       ` Cong Wang
2018-05-24  7:11         ` Peter Zijlstra [this message]
2018-05-24 22:23           ` Cong Wang

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