linux-kernel - Re: [PATCH v5 09/14] drm/syncobj: Add deadline support for syncobj waits

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Message-ID: <20230221105307.7430c301@eldfell>
Date:   Tue, 21 Feb 2023 10:53:07 +0200
From:   Pekka Paalanen <ppaalanen@...il.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>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Alex Deucher <alexander.deucher@....com>,
        Simon Ser <contact@...rsion.fr>,
        Rob Clark <robdclark@...omium.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        linux-kernel@...r.kernel.org (open list)
Subject: Re: [PATCH v5 09/14] drm/syncobj: Add deadline support for syncobj
 waits

On Mon, 20 Feb 2023 12:18:56 -0800
Rob Clark <robdclark@...il.com> wrote:

> From: Rob Clark <robdclark@...omium.org>
> 
> Add a new flag to let userspace provide a deadline as a hint for syncobj
> and timeline waits.  This gives a hint to the driver signaling the
> backing fences about how soon userspace needs it to compete work, so it
> can addjust GPU frequency accordingly.  An immediate deadline can be
> given to provide something equivalent to i915 "wait boost".
> 
> v2: Use absolute u64 ns value for deadline hint, drop cap and driver
>     feature flag in favor of allowing count_handles==0 as a way for
>     userspace to probe kernel for support of new flag
> 
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
>  drivers/gpu/drm/drm_syncobj.c | 59 +++++++++++++++++++++++++++--------
>  include/uapi/drm/drm.h        |  5 +++
>  2 files changed, 51 insertions(+), 13 deletions(-)

...

> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 642808520d92..aefc8cc743e0 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -887,6 +887,7 @@ struct drm_syncobj_transfer {
>  #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_ALL (1 << 0)
>  #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT (1 << 1)
>  #define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AVAILABLE (1 << 2) /* wait for time point to become available */
> +#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_DEADLINE (1 << 3) /* set fence deadline based to deadline_nsec/sec */

Hi,

where is the UAPI documentation explaining what is a "fence deadline"
and what setting it does here?

btw. no nsec/sec anymore.


Thanks,
pq


>  struct drm_syncobj_wait {
>  	__u64 handles;
>  	/* absolute timeout */
> @@ -895,6 +896,8 @@ struct drm_syncobj_wait {
>  	__u32 flags;
>  	__u32 first_signaled; /* only valid when not waiting all */
>  	__u32 pad;
> +	/* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
> +	__u64 deadline_ns;
>  };
>  
>  struct drm_syncobj_timeline_wait {
> @@ -907,6 +910,8 @@ struct drm_syncobj_timeline_wait {
>  	__u32 flags;
>  	__u32 first_signaled; /* only valid when not waiting all */
>  	__u32 pad;
> +	/* Deadline hint to set on backing fence(s) in CLOCK_MONOTONIC: */
> +	__u64 deadline_ns;
>  };
>  
>  


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