Messages in this thread | | | Date | Sun, 10 Sep 2023 19:20:23 +0100 | From | Qais Yousef <> | Subject | Re: [RFC PATCH 0/7] sched: cpufreq: Remove magic margins |
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On 09/07/23 13:53, Peter Zijlstra wrote: > On Thu, Sep 07, 2023 at 08:48:08AM +0100, Lukasz Luba wrote: > > > > Hehe. That's because they're not really periodic ;-) > > > > They are periodic in a sense, they wake up every 16ms, but sometimes > > they have more work. It depends what is currently going in the game > > and/or sometimes the data locality (might not be in cache). > > > > Although, that's for games, other workloads like youtube play or this > > one 'Yahoo browser' (from your example) are more 'predictable' (after > > the start up period). And I really like the potential energy saving > > there :) > > So everything media is fundamentally periodic, you're hard tied to the > framerate / audio-buffer size etc.. > > Also note that the traditional periodic task model from the real-time > community has the notion of WCET, which completely covers this > fluctuation in frame-to-frame work, it only considers the absolute worst > case. > > Now, practically, that stinks, esp. when you care about batteries, but > it does not mean these tasks are not periodic.
piecewise periodic?
> Many extentions to the periodic task model are possible, including > things like average runtime with bursts etc.. all have their trade-offs.
The challenge we have is the endless number of workloads we need to cater for.. Or you think one of these models can actually scale to that?
Thanks!
-- Qais Yousef
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