From: Peter Zijlstra <peterz@infradead.org>
To: Yuyang Du <yuyang.du@intel.com>
Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, pjt@google.com,
bsegall@google.com, morten.rasmussen@arm.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com
Subject: Re: [PATCH 1/4] sched/fair: Generalize the load/util averages resolution definition
Date: Mon, 5 Oct 2015 12:52:09 +0200 [thread overview]
Message-ID: <20151005105209.GG2903@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <1443981419-16665-2-git-send-email-yuyang.du@intel.com>
On Mon, Oct 05, 2015 at 01:56:56AM +0800, Yuyang Du wrote:
> Metric needs certain resolution to allow detail we can look into,
> which also determines the range of the metric.
>
> For instance, increasing the resolution of [0, 1] (two levels), one
> can multiply 1024 and get [0..1024] (1025 levels).
>
> /*
> + * Integer metrics need certain resolution to allow how much detail we
> + * can look into, e.g., load, load_avg, util_avg, freq, and capacity.
> + * We define a basic resolution constant number, and then formalize
> + * all these metrics based on that basic resolution.
> + */
> +# define SCHED_RESOLUTION_SHIFT 10
> +# define SCHED_RESOLUTION_SCALE (1L << SCHED_RESOLUTION_SHIFT)
> +
> +/*
I find all that most confusing, maybe just refer to fixed point
arithmetic, that's a well defined and well understood concept.
next prev parent reply other threads:[~2015-10-05 10:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-04 17:56 [PATCH 0/4] sched/fair: Clean up sched metric definitions Yuyang Du
2015-10-04 17:56 ` [PATCH 1/4] sched/fair: Generalize the load/util averages resolution definition Yuyang Du
2015-10-05 7:04 ` Ingo Molnar
2015-10-06 8:00 ` Yuyang Du
2015-10-09 23:04 ` Yuyang Du
2015-10-05 10:52 ` Peter Zijlstra [this message]
2015-10-04 17:56 ` [PATCH 2/4] sched/fair: Remove SCHED_LOAD_SHIFT and SCHED_LOAD_SCALE Yuyang Du
2015-10-06 9:29 ` Vincent Guittot
2015-10-04 17:56 ` [PATCH 3/4] sched/fair: Remove scale_load_down() for load_avg Yuyang Du
2015-10-04 17:56 ` [PATCH 4/4] sched/fair: Rename scale_load() and scale_load_down() Yuyang Du
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