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

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Message-ID: <CAF6AEGtd_9JYtPU-AGmZY0My_d48rSSWQiD-efbR2KFxD-+tTA@mail.gmail.com>
Date:   Tue, 21 Feb 2023 09:25:18 -0800
From:   Rob Clark <robdclark@...il.com>
To:     Pekka Paalanen <ppaalanen@...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>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 09/14] drm/syncobj: Add deadline support for syncobj waits

On Tue, Feb 21, 2023 at 12:53 AM Pekka Paalanen <ppaalanen@...il.com> wrote:
>
> 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?

It's with the rest of the drm_syncobj UAPI docs ;-)

BR,
-R

> 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;
> >  };
> >
> >
>