Messages in this thread | | | Date | Wed, 12 Jul 2017 15:28:24 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH RFC v4] cpufreq: schedutil: Make iowait boost more energy efficient |
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On Wed, Jul 12, 2017 at 03:16:23PM +0530, Viresh Kumar wrote:
> No, I wasn't clear enough. Sorry about that. Lemme try again: > > Suppose min freq is 500 MHz and Max is 2 GHz. The iowait-boost is > set to 1 GHz right now (because of previous events with IOWAIT flag > set), and sugov_set_iowait_boost() gets called again with IOWAIT flag, > we boost the iowait-boost value to 2 GHz. We are in the rate_limit_us > window right now, we return without changing the frequency. > > If the next call into the schedutil governor happens due to normal > util-update, flags will be passed as 0. With the current patch, we > will bring iowait-boost back to 1 GHz (before updating the real > frequency to 2 GHz) as the prev-iowait-boost boolean would be set. > > And even if the task is periodically getting queued after IOWAIT, > actual boosting may not happen at all in some cases.
Hmm, so you're worried about that ratelimit stuff? Shouldn't we fix that independently -- IIRC Rafael proposed a max-filter over the window.
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