linux-kernel - Re: [GIT PULL] ring-buffer: Allow for rescheduling when removing pages

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Date:   Wed, 19 Sep 2018 20:55:20 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vaibhav Nagarnaik <vnagarnaik@...gle.com>,
        Jason Behmer <jbehmer@...gle.com>, stable@...r.kernel.org
Subject: Re: [GIT PULL] ring-buffer: Allow for rescheduling when removing
 pages

On Wed, Sep 19, 2018 at 09:39:23AM -0400, Steven Rostedt wrote:
> On Wed, 19 Sep 2018 08:07:06 +0200
> Greg Kroah-Hartman <gregkh@...uxfoundation.org> wrote:
> 
> > On Tue, Sep 18, 2018 at 07:14:13PM -0400, Steven Rostedt wrote:
> > > 
> > > Linus (aka Greg),
> > > 
> > > Vaibhav Nagarnaik found that modifying the ring buffer size could cause
> > > a huge latency in the system because it does a while loop to free pages
> > > without releasing the CPU (on non preempt kernels). In a case where there
> > > are hundreds of thousands of pages to free it could actually cause a system
> > > stall. A properly place cond_resched() solves this issue.
> > > 
> > > 
> > > Please pull the latest trace-v4.19-rc4 tree, which can be found at:
> > > 
> > > 
> > >   git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
> > > trace-v4.19-rc4  
> > 
> > Ick, line wrapping makes it hard to cut/paste :(
> 
> ??
> 
> That's the way I have always posted pull requests. I place the branch
> on the second line. It's not line wrapped, it's a hard coded new line.
> Long ago I was told to do it that way.
> 
> Should that be changed? It would be trivial to update my scripts.

Ah, ok, that's not what I have been doing for a long time, nor what the
sub-maintainers that send stuff to me have done.  Normally it is:
	git_url tag

Like this one for perf stuff:
	https://lore.kernel.org/lkml/20171027195047.27132-1-acme@kernel.org/

If you have been doing it this way to Linus, that's fine, I can adapt :)

thanks,

greg k-h