linux-kernel - Re: [RFC PATCH 3/4] Make deadline max-heap faster avoiding real swaps on heapify ops.

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Date:	Mon, 8 Aug 2016 16:04:51 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Tommaso Cucinotta <tommaso.cucinotta@...up.it>
Cc:	Luca Abeni <luca.abeni@...tn.it>,
	Juri Lelli <juri.lelli@...il.com>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	linux-dl@...is.sssup.it, Juri Lelli <juri.lelli@....com>
Subject: Re: [RFC PATCH 3/4] Make deadline max-heap faster avoiding real
 swaps on heapify ops.

On Tue, Jul 19, 2016 at 11:44:52AM +0200, Tommaso Cucinotta wrote:
> This change achieves up to 10% of speed-up for cpudl_set() calls, as
> measured with a andomly generated workload of 1K,10K,100K random heap
> insertions and deletions (75% cpudl_set() calls with is_valid=1 and
> 25% with is_valid=0), and randomly generated cpu IDs, with up to 256
> CPUs, as measured on an Intel Core2 Duo.

Changelog fails to explain _what_ the change is.

Some details on the change in implementation and why this is faster
would be good.