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Date:   Mon, 26 Apr 2021 10:09:47 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Ed Tsai <ed.tsai@mediatek.com>, mingo@redhat.com,
        linux-kernel@vger.kernel.org, stanley.chu@mediatek.com,
        loda.chou@mediatek.com
Subject: Re: [PATCH 1/1] sched: remove the redundant 'success' in the sched
 tracepoint
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References: <20210422122226.9415-1-ed.tsai@mediatek.com>
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 <0fd8e103cc2886724979f7d93066b86b773032eb.camel@mediatek.com>
 <20210425175426.23f292a9@oasis.local.home>
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On Sun, Apr 25, 2021 at 05:54:26PM -0400, Steven Rostedt wrote:
> On Fri, 23 Apr 2021 08:38:22 +0800
> Ed Tsai <ed.tsai@mediatek.com> wrote:
> 
> > On Thu, 2021-04-22 at 11:46 -0400, Steven Rostedt wrote:
> > > On Thu, 22 Apr 2021 20:22:26 +0800
> > > Ed Tsai <ed.tsai@mediatek.com> wrote:
> > >   
> > > > 'success' is left here for a long time and also it is meaningless
> > > > for the upper user. Just remove it.  
> > > 
> > > Have you tested all userspace code that might use this?
> > > 
> > > This is the "poster boy" example of why Peter Zijlstra hates trace
> > > events ;-)
> > > 
> > > I know I've updated trace-cmd to check to see if this field exits
> > > before
> > > depending on it, but there may be some other tools that may not.
> > > Perhaps
> > > nothing will break.
> > > 
> > > I'm all for this change, but be ware, it might be reverted if there's
> > > some
> > > tool out that that expects it to exist. This is why it hasn't been
> > > removed.
> > > 
> > > -- Steve  
> > 
> > It is left here over 5 years. Old userspace code need this entry and
> > also someone may use it for a new tool. I hate this but it is a problem
> > should be resolved for the kernel or ignore just fine.
> > 
> 
> I'm willing to take this, with a note that if anyone complains, it may
> be reverted. But as it goes with Linus's rule about breaking user
> space. If you break user space, and nobody notices, you didn't really
> break it!

LatencyTop was I think the offender at the time, but I can't really
remember. Anyway, glad to be rid of it, if we get away with it that is
;-)