Messages in this thread | | | Subject | Re: [PATCH] drm/panfrost: Use delayed timer as default in devfreq profile | From | Steven Price <> | Date | Wed, 13 Jan 2021 15:35:37 +0000 |
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On 05/01/2021 16:41, Lukasz Luba wrote: > Devfreq framework supports 2 modes for monitoring devices. > Use delayed timer as default instead of deferrable timer > in order to monitor the GPU status regardless of CPU idle. > > Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Looks reasonable to me.
Reviewed-by: Steven Price <steven.price@arm.com>
I'll apply to drm-misc-next.
> --- > Hi all, > > This is just a simple change but has impact on reliable polling mode > with guaranteed sampling rate. The devfreq framework has 2 modes for > checking the device status which updates the statistics. When the > default mode is used (deferred work) it could happen that the > framework won't check the device, if the CPU which was running devfreq > code went idle. In deferred mode, the deferred timer is not fired, > thus framework won't check the device status. > > The log below is taken when glxgears was running. It can be seen that > periodic checks are missing (should be every 50ms). > > ---------------------------------------------------------------------- > > [ 128.046555] panfrost ff9a0000.gpu: busy 18029406 total 67940380 26 % freq 200 MHz > [ 128.110538] panfrost ff9a0000.gpu: busy 7975930 total 63980997 12 % freq 200 MHz > [ 128.210606] panfrost ff9a0000.gpu: busy 21148792 total 100074440 21 % freq 200 MHz > [ 128.594638] panfrost ff9a0000.gpu: busy 53739467 total 384032219 13 % freq 200 MHz > [ 129.178749] panfrost ff9a0000.gpu: busy 89206245 total 584111500 15 % freq 200 MHz > [ 129.294601] panfrost ff9a0000.gpu: busy 16446118 total 115852915 14 % freq 200 MHz > [ 129.762616] panfrost ff9a0000.gpu: busy 71481587 total 468015722 15 % freq 200 MHz > [ 129.874762] panfrost ff9a0000.gpu: busy 15614112 total 112139938 13 % freq 200 MHz > [ 130.026585] panfrost ff9a0000.gpu: busy 21397620 total 151821546 14 % freq 200 MHz > [ 130.110536] panfrost ff9a0000.gpu: busy 21429365 total 83952016 25 % freq 200 MHz > [ 130.178524] panfrost ff9a0000.gpu: busy 16458197 total 67989072 24 % freq 200 MHz > [ 130.246528] panfrost ff9a0000.gpu: busy 9876225 total 68004030 14 % freq 200 MHz > [ 130.310529] panfrost ff9a0000.gpu: busy 9211725 total 64000524 14 % freq 200 MHz > [ 130.410528] panfrost ff9a0000.gpu: busy 21780828 total 99999250 21 % freq 200 MHz > > ---------------------------------------------------------------------- > > It has impact on devfreq cooling and thermal governor. They rely on these > statistics, but sometimes the data is stale. > > This patch switches to more reliable devfreq mode, which uses delayed work. > > Regards, > Lukasz > > > drivers/gpu/drm/panfrost/panfrost_devfreq.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_devfreq.c b/drivers/gpu/drm/panfrost/panfrost_devfreq.c > index f44d28fad085..56b3f5935703 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_devfreq.c > +++ b/drivers/gpu/drm/panfrost/panfrost_devfreq.c > @@ -76,6 +76,7 @@ static int panfrost_devfreq_get_dev_status(struct device *dev, > } > > static struct devfreq_dev_profile panfrost_devfreq_profile = { > + .timer = DEVFREQ_TIMER_DELAYED, > .polling_ms = 50, /* ~3 frames */ > .target = panfrost_devfreq_target, > .get_dev_status = panfrost_devfreq_get_dev_status, >
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