linux-kernel - Re: [PATCH v9 15/15] drm/i915: Add deadline based boost support

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Date:   Thu, 2 Mar 2023 22:21:13 -0500
From:   Rodrigo Vivi <rodrigo.vivi@...el.com>
To:     Rob Clark <robdclark@...il.com>
CC:     <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, Daniel Vetter <daniel@...ll.ch>,
        Christian König 
        <ckoenig.leichtzumerken@...il.com>,
        Michel Dänzer <michel@...nzer.net>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>,
        Alex Deucher <alexander.deucher@....com>,
        Pekka Paalanen <ppaalanen@...il.com>,
        Simon Ser <contact@...rsion.fr>,
        Luben Tuikov <luben.tuikov@....com>,
        Rob Clark <robdclark@...omium.org>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        "Joonas Lahtinen" <joonas.lahtinen@...ux.intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        David Airlie <airlied@...il.com>,
        "Sumit Semwal" <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        <intel-gfx@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DMA BUFFER SHARING FRAMEWORK" 
        <linux-media@...r.kernel.org>,
        "moderated list:DMA BUFFER SHARING FRAMEWORK" 
        <linaro-mm-sig@...ts.linaro.org>
Subject: Re: [PATCH v9 15/15] drm/i915: Add deadline based boost support

On Thu, Mar 02, 2023 at 03:53:37PM -0800, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
>

missing some wording here...

> v2: rebase
> 
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
>  drivers/gpu/drm/i915/i915_request.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 7503dcb9043b..44491e7e214c 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -97,6 +97,25 @@ static bool i915_fence_enable_signaling(struct dma_fence *fence)
>  	return i915_request_enable_breadcrumb(to_request(fence));
>  }
>  
> +static void i915_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
> +{
> +	struct i915_request *rq = to_request(fence);
> +
> +	if (i915_request_completed(rq))
> +		return;
> +
> +	if (i915_request_started(rq))
> +		return;

why do we skip the boost if already started?
don't we want to boost the freq anyway?

> +
> +	/*
> +	 * TODO something more clever for deadlines that are in the
> +	 * future.  I think probably track the nearest deadline in
> +	 * rq->timeline and set timer to trigger boost accordingly?
> +	 */

I'm afraid it will be very hard to find some heuristics of what's
late enough for the boost no?
I mean, how early to boost the freq on an upcoming deadline for the
timer?

> +
> +	intel_rps_boost(rq);
> +}
> +
>  static signed long i915_fence_wait(struct dma_fence *fence,
>  				   bool interruptible,
>  				   signed long timeout)
> @@ -182,6 +201,7 @@ const struct dma_fence_ops i915_fence_ops = {
>  	.signaled = i915_fence_signaled,
>  	.wait = i915_fence_wait,
>  	.release = i915_fence_release,
> +	.set_deadline = i915_fence_set_deadline,
>  };
>  
>  static void irq_execute_cb(struct irq_work *wrk)
> -- 
> 2.39.1
>