Re: [PATCH] drm/amdgpu: use the last IB as gang leader v2

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

I wanted to push this directly to drm-misc-fixes.

But going to add one in case someone tries to backport the gang submit 
changes.

Regards,
Christian.

Am 15.11.22 um 15:10 schrieb Alex Deucher:
> Would be good to add a Fixes tag.
>
> Alex
>
> On Tue, Nov 15, 2022 at 9:09 AM Alex Deucher <alexdeucher@xxxxxxxxx> wrote:
> > Reviewed-by: Alex Deucher <alexander.deucher@xxxxxxx>
> >
> > On Tue, Nov 15, 2022 at 4:44 AM Christian König
> > <christian.koenig@xxxxxxx> wrote:
> > > Am 15.11.22 um 10:42 schrieb Christian König:
> > > > It turned out that not the last IB specified is the gang leader,
> > > > but instead the last job allocated.
> > > >
> > > > This is a bit unfortunate and not very intuitive for the CS
> > > > interface, so try to fix this.
> > > Alex could you take a look at this? I would really like to get this into
> > > the next -rc.
> > >
> > > Thanks,
> > > Christian.
> > >
> > > > Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> > > > ---
> > > >    drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 23 ++++++++++++++++-------
> > > >    drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h |  1 +
> > > >    2 files changed, 17 insertions(+), 7 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> > > > index 1bbd39b3b0fc..fbdf139cf497 100644
> > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> > > > @@ -109,6 +109,7 @@ static int amdgpu_cs_p1_ib(struct amdgpu_cs_parser *p,
> > > >                return r;
> > > >
> > > >        ++(num_ibs[r]);
> > > > +     p->gang_leader_idx = r;
> > > >        return 0;
> > > >    }
> > > >
> > > > @@ -300,7 +301,7 @@ static int amdgpu_cs_pass1(struct amdgpu_cs_parser *p,
> > > >                if (ret)
> > > >                        goto free_all_kdata;
> > > >        }
> > > > -     p->gang_leader = p->jobs[p->gang_size - 1];
> > > > +     p->gang_leader = p->jobs[p->gang_leader_idx];
> > > >
> > > >        if (p->ctx->vram_lost_counter != p->gang_leader->vram_lost_counter) {
> > > >                ret = -ECANCELED;
> > > > @@ -1194,16 +1195,18 @@ static int amdgpu_cs_sync_rings(struct amdgpu_cs_parser *p)
> > > >                        return r;
> > > >        }
> > > >
> > > > -     for (i = 0; i < p->gang_size - 1; ++i) {
> > > > +     for (i = 0; i < p->gang_size; ++i) {
> > > > +             if (p->jobs[i] == leader)
> > > > +                     continue;
> > > > +
> > > >                r = amdgpu_sync_clone(&leader->sync, &p->jobs[i]->sync);
> > > >                if (r)
> > > >                        return r;
> > > >        }
> > > >
> > > > -     r = amdgpu_ctx_wait_prev_fence(p->ctx, p->entities[p->gang_size - 1]);
> > > > +     r = amdgpu_ctx_wait_prev_fence(p->ctx, p->entities[p->gang_leader_idx]);
> > > >        if (r && r != -ERESTARTSYS)
> > > >                DRM_ERROR("amdgpu_ctx_wait_prev_fence failed.\n");
> > > > -
> > > >        return r;
> > > >    }
> > > >
> > > > @@ -1237,9 +1240,12 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
> > > >        for (i = 0; i < p->gang_size; ++i)
> > > >                drm_sched_job_arm(&p->jobs[i]->base);
> > > >
> > > > -     for (i = 0; i < (p->gang_size - 1); ++i) {
> > > > +     for (i = 0; i < p->gang_size; ++i) {
> > > >                struct dma_fence *fence;
> > > >
> > > > +             if (p->jobs[i] == leader)
> > > > +                     continue;
> > > > +
> > > >                fence = &p->jobs[i]->base.s_fence->scheduled;
> > > >                r = amdgpu_sync_fence(&leader->sync, fence);
> > > >                if (r)
> > > > @@ -1275,7 +1281,10 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
> > > >        list_for_each_entry(e, &p->validated, tv.head) {
> > > >
> > > >                /* Everybody except for the gang leader uses READ */
> > > > -             for (i = 0; i < (p->gang_size - 1); ++i) {
> > > > +             for (i = 0; i < p->gang_size; ++i) {
> > > > +                     if (p->jobs[i] == leader)
> > > > +                             continue;
> > > > +
> > > >                        dma_resv_add_fence(e->tv.bo->base.resv,
> > > >                                           &p->jobs[i]->base.s_fence->finished,
> > > >                                           DMA_RESV_USAGE_READ);
> > > > @@ -1285,7 +1294,7 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
> > > >                e->tv.num_shared = 0;
> > > >        }
> > > >
> > > > -     seq = amdgpu_ctx_add_fence(p->ctx, p->entities[p->gang_size - 1],
> > > > +     seq = amdgpu_ctx_add_fence(p->ctx, p->entities[p->gang_leader_idx],
> > > >                                   p->fence);
> > > >        amdgpu_cs_post_dependencies(p);
> > > >
> > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h
> > > > index cbaa19b2b8a3..f80adf9069ec 100644
> > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h
> > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.h
> > > > @@ -54,6 +54,7 @@ struct amdgpu_cs_parser {
> > > >
> > > >        /* scheduler job objects */
> > > >        unsigned int            gang_size;
> > > > +     unsigned int            gang_leader_idx;
> > > >        struct drm_sched_entity *entities[AMDGPU_CS_GANG_SIZE];
> > > >        struct amdgpu_job       *jobs[AMDGPU_CS_GANG_SIZE];
> > > >        struct amdgpu_job       *gang_leader;