linux-kernel - Re: [PATCH] timers: Make the lower-level timer function first call than higher-level

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Message-ID: <CALAqxLUUpGfDzOoDyPA4LFyzFyVmiT4wKLUWa5Tin8eypJBCDQ@mail.gmail.com>
Date:   Mon, 19 Nov 2018 10:16:15 -0800
From:   John Stultz <john.stultz@...aro.org>
To:     Muchun Song <smuchun@...il.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Stephen Boyd <sboyd@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] timers: Make the lower-level timer function first call
 than higher-level

On Mon, Nov 19, 2018 at 6:10 AM, Muchun Song <smuchun@...il.com> wrote:
> The elements of the heads array are a linked list of timer events that
> expire at the current time. And it can contain up to LVL_DEPTH levels
> and the lower the level represents the smaller the time granularity.
>
> Now the result is that the function, which will be called when the timer
> expires, in the higher-level is called first than the lower-level function.
> I think it might be better to call the lower-level timer function first
> than the higher-level function. Because the lower-level has the smaller
> granularity and delay has less impact on higher-level. So fix it.

Interesting.

Do you have any specific examples of where this was helpful?  Maybe
data on how much this helped the case your concerned about?

thanks
-john