| Message ID | 1424963818-11931-4-git-send-email-deepak.s@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Feb 26, 2015 at 08:46:56PM +0530, deepak.s@linux.intel.com wrote: > From: Deepak S <deepak.s@linux.intel.com> > > After feedback from the hardware team, now we set the GPU min freq to RPe. > If we drop the freq to RPn, we found that the punit was not setting the > voltage to Vnn, So recommendation is to set min freq to RPe. And does it change the voltage at all? Is there really any advantage to the extra code on idle? Does efficient_freq really consume less power than min_freq when active (assuming a min_freq/efficient_freq busy workload i.e. does a workload that would be 100% busy at min_freq consume less power when run at efficient_freq)? -Chris
On Thursday 26 February 2015 09:42 PM, Chris Wilson wrote: > On Thu, Feb 26, 2015 at 08:46:56PM +0530, deepak.s@linux.intel.com wrote: >> From: Deepak S <deepak.s@linux.intel.com> >> >> After feedback from the hardware team, now we set the GPU min freq to RPe. >> If we drop the freq to RPn, we found that the punit was not setting the >> voltage to Vnn, So recommendation is to set min freq to RPe. > And does it change the voltage at all? Yes Voltage does change when we drop to RPe > Is there really any advantage to > the extra code on idle?Does efficient_freq really consume less power > than min_freq when active (assuming a min_freq/efficient_freq busy > workload i.e. does a workload that would be 100% busy at min_freq > consume less power when run at efficient_freq)? The delta voltage usage between RPn and RPe is very small like close to zero. Also, if we run workload 100% busy at Rpe we get better performance without much of voltage loss right? btw, Punit expects us to operate between Rpe & RP0. > -Chris >
On Wed, Mar 11, 2015 at 07:23:48PM +0530, Deepak S wrote: > > > On Thursday 26 February 2015 09:42 PM, Chris Wilson wrote: > >On Thu, Feb 26, 2015 at 08:46:56PM +0530, deepak.s@linux.intel.com wrote: > >>From: Deepak S <deepak.s@linux.intel.com> > >> > >>After feedback from the hardware team, now we set the GPU min freq to RPe. > >>If we drop the freq to RPn, we found that the punit was not setting the > >>voltage to Vnn, So recommendation is to set min freq to RPe. > >And does it change the voltage at all? > > Yes Voltage does change when we drop to RPe > > >Is there really any advantage to > >the extra code on idle?Does efficient_freq really consume less power > >than min_freq when active (assuming a min_freq/efficient_freq busy > >workload i.e. does a workload that would be 100% busy at min_freq > >consume less power when run at efficient_freq)? > > The delta voltage usage between RPn and RPe is very small like close to zero. > Also, if we run workload 100% busy at Rpe we get better performance without much of voltage loss right? > btw, Punit expects us to operate between Rpe & RP0. If you need 100% at RPe you obviously can't run at RPn (since that would lead to dropped frames). The question is if you have a workload that requires 100% at RPn do you save power if you ran e.g. 80% at RPe? If the punit only works reliably between RPe and RP0, then the current RPn is a bit of a misnomer, and that should be the explanation in the commit log. Definitely do not conflate the idea of executing at RPn and RPe with the idea of idling at RPn or RPe - this patch affects idle frequency. -Chris
On Wednesday 11 March 2015 07:36 PM, Chris Wilson wrote: > On Wed, Mar 11, 2015 at 07:23:48PM +0530, Deepak S wrote: >> >> On Thursday 26 February 2015 09:42 PM, Chris Wilson wrote: >>> On Thu, Feb 26, 2015 at 08:46:56PM +0530, deepak.s@linux.intel.com wrote: >>>> From: Deepak S <deepak.s@linux.intel.com> >>>> >>>> After feedback from the hardware team, now we set the GPU min freq to RPe. >>>> If we drop the freq to RPn, we found that the punit was not setting the >>>> voltage to Vnn, So recommendation is to set min freq to RPe. >>> And does it change the voltage at all? >> Yes Voltage does change when we drop to RPe >> >>> Is there really any advantage to >>> the extra code on idle?Does efficient_freq really consume less power >>> than min_freq when active (assuming a min_freq/efficient_freq busy >>> workload i.e. does a workload that would be 100% busy at min_freq >>> consume less power when run at efficient_freq)? >> The delta voltage usage between RPn and RPe is very small like close to zero. >> Also, if we run workload 100% busy at Rpe we get better performance without much of voltage loss right? >> btw, Punit expects us to operate between Rpe & RP0. > If you need 100% at RPe you obviously can't run at RPn (since that would > lead to dropped frames). The question is if you have a workload that > requires 100% at RPn do you save power if you ran e.g. 80% at RPe? We do not expect much of power saving running at RPn. If we need exact number I need to gather the data. > > If the punit only works reliably between RPe and RP0, then the current > RPn is a bit of a misnomer, and that should be the explanation in the > commit log. Definitely do not conflate the idea of executing at RPn and > RPe with the idea of idling at RPn or RPe - this patch affects idle > frequency. > -Chris > Yes I understand it affects idle freq but running at RPe gives better performance at lower voltage and also punit drops voltage to help save power I will update the commit msg to explain why we need lower freq at Rpe.
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 90cb6c9..e8bd9b9 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -4755,7 +4755,7 @@ static void cherryview_init_gt_powersave(struct drm_device *dev) dev_priv->rps.max_freq_softlimit = dev_priv->rps.max_freq; if (dev_priv->rps.min_freq_softlimit == 0) - dev_priv->rps.min_freq_softlimit = dev_priv->rps.min_freq; + dev_priv->rps.min_freq_softlimit = dev_priv->rps.efficient_freq; mutex_unlock(&dev_priv->rps.hw_lock); }