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Date: Wed, 18 Jul 2018 18:11:39 -0400
From: Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH 08/10] psi: pressure stall information for CPU, memory,
 and IO
Message-ID: <20180718221139.GF2838@cmpxchg.org>
References: <20180712172942.10094-1-hannes@cmpxchg.org>
 <20180712172942.10094-9-hannes@cmpxchg.org>
 <20180717151705.GH2494@hirez.programming.kicks-ass.net>
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To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, Linus Torvalds <torvalds@linux-foundation.org>, Tejun Heo <tj@kernel.org>, Suren Baghdasaryan <surenb@google.com>, Vinayak Menon <vinmenon@codeaurora.org>, Christopher Lameter <cl@linux.com>, Mike Galbraith <efault@gmx.de>, Shakeel Butt <shakeelb@google.com>, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com

On Tue, Jul 17, 2018 at 05:17:05PM +0200, Peter Zijlstra wrote:
> On Thu, Jul 12, 2018 at 01:29:40PM -0400, Johannes Weiner wrote:
> > @@ -457,6 +457,22 @@ config TASK_IO_ACCOUNTING
> >  
> >  	  Say N if unsure.
> >  
> > +config PSI
> > +	bool "Pressure stall information tracking"
> > +	select SCHED_INFO
> 
> What's the deal here? AFAICT it does not in fact use SCHED_INFO for
> _anything_. You just hooked into the sched_info_{en,de}queue() hooks,
> but you don't use any of the sched_info data.
> 
> So the dependency is an artificial one that should not exist.

You're right, it doesn't strictly depend on it. I'll split that out.