From: Peter Zijlstra <peterz@infradead.org>
To: Yuyang Du <yuyang.du@intel.com>
Cc: mingo@kernel.org, linux-kernel@vger.kernel.org,
bsegall@google.com, pjt@google.com, morten.rasmussen@arm.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
juri.lelli@arm.com
Subject: Re: [PATCH v2 03/12] sched/fair: Change the variable to hold the number of periods to 32bit integer
Date: Tue, 3 May 2016 10:47:42 +0200 [thread overview]
Message-ID: <20160503084742.GH3430@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1462226078-31904-4-git-send-email-yuyang.du@intel.com>
On Tue, May 03, 2016 at 05:54:29AM +0800, Yuyang Du wrote:
> In sched average update, a period is about 1ms, so a 32-bit unsigned
> integer can approximately hold a maximum of 49 (=2^32/1000/3600/24)
> days, which means it is big enough and 64-bit is needless.
This fails to explain _why_ 49 days is enough. And what the 49 days is
enough for.
What happens when a task sleeps for more than 49 days?
next prev parent reply other threads:[~2016-05-03 8:47 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-02 21:54 [PATCH v2 00/12] sched/fair: Optimize and clean up sched averages Yuyang Du
2016-05-02 21:54 ` [PATCH v2 01/12] sched/fair: Optimize sum computation with a lookup table Yuyang Du
2016-05-05 9:41 ` [tip:sched/core] " tip-bot for Yuyang Du
2016-05-02 21:54 ` [PATCH v2 02/12] sched/fair: Rename variable names for sched averages Yuyang Du
2016-05-02 21:54 ` [PATCH v2 03/12] sched/fair: Change the variable to hold the number of periods to 32bit integer Yuyang Du
2016-05-03 8:47 ` Peter Zijlstra [this message]
2016-05-02 21:54 ` [PATCH v2 04/12] sched/fair: Add __always_inline compiler attribute to __accumulate_sum() Yuyang Du
2016-05-02 21:54 ` [PATCH v2 05/12] sched/fair: Optimize __update_sched_avg() Yuyang Du
2016-05-03 8:49 ` Peter Zijlstra
2016-05-02 21:54 ` [PATCH v2 06/12] documentation: Add scheduler/sched-avg.txt Yuyang Du
2016-05-03 8:50 ` Peter Zijlstra
2016-05-02 21:54 ` [PATCH v2 07/12] sched/fair: Generalize the load/util averages resolution definition Yuyang Du
2016-05-02 21:54 ` [PATCH v2 08/12] sched/fair: Remove SCHED_LOAD_SHIFT and SCHED_LOAD_SCALE Yuyang Du
2016-05-02 21:54 ` [PATCH v2 09/12] sched/fair: Add introduction to the sched average metrics Yuyang Du
2016-05-02 21:54 ` [PATCH v2 10/12] sched/fair: Remove scale_load_down() for load_avg Yuyang Du
2016-05-02 21:54 ` [PATCH v2 11/12] sched/fair: Rename scale_load() and scale_load_down() Yuyang Du
2016-05-02 21:54 ` [PATCH v2 12/12] sched/fair: Enable increased scale for kernel load Yuyang Du
2016-05-02 22:08 ` [PATCH v2 00/12] sched/fair: Optimize and clean up sched averages Yuyang Du
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