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Date: Fri, 3 Aug 2018 19:15:38 +0200
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 8/9] psi: pressure stall information for CPU, memory, and
 IO
Message-ID: <20180803171538.GD2494@hirez.programming.kicks-ass.net>
References: <20180801151958.32590-1-hannes@cmpxchg.org>
 <20180801151958.32590-9-hannes@cmpxchg.org>
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To: Johannes Weiner <hannes@cmpxchg.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>, Daniel Drake <drake@endlessm.com>, Vinayak Menon <vinmenon@codeaurora.org>, Christopher Lameter <cl@linux.com>, Mike Galbraith <efault@gmx.de>, Shakeel Butt <shakeelb@google.com>, Peter Enderborg <peter.enderborg@sony.com>, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com

On Wed, Aug 01, 2018 at 11:19:57AM -0400, Johannes Weiner wrote:
> +	/* total= */
> +	for (s = 0; s < NR_PSI_STATES - 1; s++)
> +		group->total[s] += div_u64(deltas[s], max(nonidle_total, 1UL));

Just a nit; probably not worth fixing.

This looses the remainder of that division. But since the divisor is
variable it becomes really hard to not loose something at some point.