[Intel-gfx] [PATCH v2 1/3] drm/i915: add rc6 residency times to debugfs

Eugeni Dodonov eugeni at dodonov.net
Mon Mar 26 14:33:51 CEST 2012

On Mon, Mar 26, 2012 at 06:34, Daniel Vetter <daniel at ffwll.ch> wrote:

> On Sun, Mar 25, 2012 at 05:33:27PM -0700, Ben Widawsky wrote:
> > RC6 residency should be in intervals of 1.28us, and the counter wraps.
> > Here is an example using awk to get the various RC6 and RC6+ residency
> > times in seconds, since boot.
> >
> > cat /sys/kernel/debug/dri/0/i915_drpc_info  | grep residency | awk -F':'
> -F' '  '{print $5 * 1.28 / 1000000}'
> >
> > This is primarily for debug, and QA/application developers using the
> > sysfs interface looking for more insight.
> >
> > Untested on IVB.
> Tested on my ivb, seems to yield sane numbers for the default
> configuration (i.e. enable rc+rc6p, disable rc6pp).

Yeah, it should work on IVB except for some strange behavior sometimes (I
noticed that on IVB we sometimes get into RC6 even if we pass the
i915_enable_rc6=0 parameter). I don't know if it is Bios playing some
tricks with us or something changed in the mailbox communication, but no
harm came from this so far. I'll see what is going on there.

But for the patch itself:
Reviewed-by: Eugeni Dodonov <eugeni.dodonov at gmail.com>

Nothing like new and shiny powertop power-saving options :).

Eugeni Dodonov
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