linux-kernel - Re: [PATCH v3 04/10] sched/fair: rework load

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Message-ID: <df8cff7b-a83c-42d1-f1c7-1a711dc1b2ce@arm.com>
Date:   Tue, 8 Oct 2019 18:36:51 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, Phil Auld <pauld@...hat.com>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        Quentin Perret <quentin.perret@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <Morten.Rasmussen@....com>,
        Hillf Danton <hdanton@...a.com>
Subject: Re: [PATCH v3 04/10] sched/fair: rework load_balance

On 08/10/2019 17:39, Valentin Schneider wrote:
>>
>> But -fno-strict-overflow mandates 2s complement for all such signed
>> issues.
>>
> 
> So then there really shouldn't be any ambiguity. I have no idea if
> -fno-strict-overflow then also lifts the undefinedness of the right shifts,
> gotta get my spade and dig some more.
> 

Bleh, no luck really.

Thinking about it some more you can't overflow by right shifting
(logical/arithmetic), so I dunno if signed right shift counts as "such
signed issues".