Re: [PATCH v2] drm/i915: Modifying RC6 Promotion timer for Media workloads.

From: Deepak S <deepak.s@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>,
	Daniel Vetter <daniel@ffwll.ch>,
	intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH v2] drm/i915: Modifying RC6 Promotion timer for Media workloads.
Date: Wed, 11 Mar 2015 19:29:48 +0530	[thread overview]
Message-ID: <55004A54.4010409@linux.intel.com> (raw)
In-Reply-To: <20150311135604.GB13727@nuc-i3427.alporthouse.com>


On Wednesday 11 March 2015 07:26 PM, Chris Wilson wrote:
> On Wed, Mar 11, 2015 at 07:07:12PM +0530, Deepak S wrote:
>>
>> On Friday 06 March 2015 10:10 PM, Daniel Vetter wrote:
>>> On Thu, Mar 05, 2015 at 09:27:59PM +0530, deepak.s@linux.intel.com wrote:
>>>> From: Deepak S <deepak.s@linux.intel.com>
>>>>
>>>> In normal cases, RC6 promotion timer is 1700us/500us. This will
>>>> result in more time spent in C1 state. For more residency in
>>>> C6 in case of media workloads, this is changed to 250us.
>>>> Not doing this for 3D workloads as too many C6-C0
>>>> transition delays can result in performance impact.
>>>>
>>>> v2: Extend GPU busy & idle detection framework for rc6 Promotion
>>>> timer changes (Chris)
>>>>
>>>> Signed-off-by: Deepak S <deepak.s@linux.intel.com>
>>> I've thougth Chris' idea was to put this into the gen6_rps_boost/idle
>>> functions? You could check from within them I think for whether the vcs is
>>> still busy ... One more comment below.
>>> -Daniel
>> Hi Daniel,
>>
>> gen6_rps_boost/idle will be called only for RCS right? Also we get gen6_rps_boost during  __wait_request
>> But we want to program promotion timer when we add request to VCS to apply the value immediately.
> It's gen6_rps_busy/gen6_rps_idle. They are called from intel_mark_busy
> and intel_mark_idle. It is intel_mark_busy/intel_mark_idle that we want
> to extend to cover the VCS case as well. I think if you add a ring
> parameter to the functions, we can start specialising per ring and
> global state changes. You will then also be in a position to judge what
> is the best idle timer (and consider making i915_gem_idle_work_handler
> per ring). The goal is simply to evolve the current infrastucture for
> idle/busyness handling to cover your use case as well (and hopefully in
> the process improving the old/general cases).
> -Chris
>
Thanks Chris. extending intel_mark_busy/intel_mark_idle
makes sense. I will work on adding the change

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