linux-kernel - Re: [PATCH v8 00/25] timer: Move from a push remote at enqueue to a pull at expiry model

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Message-ID: <87jzri90nm.fsf@somnus>
Date:   Thu, 19 Oct 2023 15:55:57 +0200
From:   Anna-Maria Behnsen <anna-maria@...utronix.de>
To:     K Prateek Nayak <kprateek.nayak@....com>,
        linux-kernel@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        John Stultz <jstultz@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Eric Dumazet <edumazet@...gle.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Arjan van de Ven <arjan@...radead.org>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Rik van Riel <riel@...riel.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sebastian Siewior <bigeasy@...utronix.de>,
        Giovanni Gherdovich <ggherdovich@...e.cz>,
        Lukasz Luba <lukasz.luba@....com>,
        "Gautham R . Shenoy" <gautham.shenoy@....com>,
        Srinivas Pandruvada <srinivas.pandruvada@...el.com>
Subject: Re: [PATCH v8 00/25] timer: Move from a push remote at enqueue to a
 pull at expiry model

Hello Prateek,

K Prateek Nayak <kprateek.nayak@....com> writes:

> Hello Anna-Maria,
>
> Happy to report I don't see any regression with this version of series.
> I'll leave the detailed report below.

[...]

> Thank you for debugging and helping fix the tbench regression.
> If the series does not change drastically, feel free to add:
>
> Tested-by: K Prateek Nayak <kprateek.nayak@....com>
>

Thanks a lot for all the testing you did! When posting v9, I'll
summarize the changes and if required, I'll ask for testing support, if
it is ok?

>> 
>> Possible Next Steps
>> ~~~~~~~~~~~~~~~~~~~
>> 
>> Simple deferrable timers are no longer required as they can be converted to
>> global timers. If a CPU goes idle, a formerly deferrable timer will not
>> prevent the CPU to sleep as long as possible. Only the last migrator CPU
>> has to take care of them. Deferrable timers with timer pinned flags needs
>> to be expired on the specified CPU but must not prevent CPU from going
>> idle. They require their own timer base which is never taken into account
>> when calculating the next expiry time. This conversation and required
>> cleanup will be done in a follow up series.
>> 
>
> I'll keep an eye out for future versions for testing.

I'll keep you in the loop.

Thanks,

	Anna-Maria