[PATCH 1/2] drm/amdgpu:fix gfx ib schedule
Liu, Monk
Monk.Liu at amd.com
Fri Aug 26 03:39:48 UTC 2016
But for VI. My patch will reduce those 5 redundant SB and one SB can always use ping-pong buffer,
so the performance looks raised around 5%.
BR Monk
-----Original Message-----
From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf Of Liu, Monk
Sent: Friday, August 26, 2016 11:01 AM
To: Deucher, Alexander <Alexander.Deucher at amd.com>; amd-gfx at lists.freedesktop.org
Subject: RE: [PATCH 1/2] drm/amdgpu:fix gfx ib schedule
Not needed at least in windows kmd, I don't know if it is out of what reason, with my guess:
1, CI doesn’t support world switch, so no need for the SWITCH_BUFFER at end (only one SB at end is for world switch).
2, I don’t know if that limit can also applied on CI (limit is CE can at most ahead of DE by a certain number DW )
So I think CE can keep the original logic.
BR Monk
-----Original Message-----
From: Deucher, Alexander
Sent: Thursday, August 25, 2016 9:33 PM
To: Liu, Monk <Monk.Liu at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Liu, Monk <Monk.Liu at amd.com>
Subject: RE: [PATCH 1/2] drm/amdgpu:fix gfx ib schedule
> -----Original Message-----
> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
> Of Monk Liu
> Sent: Thursday, August 25, 2016 1:58 AM
> To: amd-gfx at lists.freedesktop.org
> Cc: Liu, Monk
> Subject: [PATCH 1/2] drm/amdgpu:fix gfx ib schedule
>
> for GFX 8, originally we use double switch_buffer to prevents CE go
> ahead of DE, thus it can avoid VM fault in case of VM_flush not
> finish. but double SWITCH_BUFFER drops performance, and world switch
> preemption requires that only one SWITCH_BUFFER is needed at the end
> of DMAframe.
>
> to Pevent CE vm fault without double switch_buffer, we need to insert
> 128 dw NOP after vm flush because CE and DE can have at most 128 DW
> gap from hw perspective.
>
> Even no context switch, SWITCH_BUFFER is encouraged to use to get
> better CE performance.
>
> Change-Id: Ifdabf23f97e74156c1f66dddd0918ea7ffcddb20
> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 ++
> drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c | 8 ++++++++
> drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c | 28 +++++++++++++-------------
What about gfx7? Does that need similar fixes?
Alex
> --
> 3 files changed, 23 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index cb0098a..a935831 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -338,6 +338,7 @@ struct amdgpu_ring_funcs {
> void (*end_use)(struct amdgpu_ring *ring);
> void (*emit_wreg) (struct amdgpu_ring *ring, uint32_t offset,
> uint32_t val);
> void (*emit_rreg) (struct amdgpu_ring *ring, uint32_t offset);
> + void (*emit_switch_buffer) (struct amdgpu_ring *ring);
> };
>
> /*
> @@ -2372,6 +2373,7 @@ amdgpu_get_sdma_instance(struct amdgpu_ring
> *ring)
> #define amdgpu_ring_emit_hdp_invalidate(r) (r)->funcs-
> >emit_hdp_invalidate((r))
> #define amdgpu_ring_emit_wreg(r, i, v) (r)->funcs->emit_wreg((r),
> (i), (v)) #define amdgpu_ring_emit_rreg(r, i)
> (r)->funcs->emit_rreg((r), (i))
> +#define amdgpu_ring_emit_switch_buffer(r) (r)->funcs-
> >emit_switch_buffer((r))
> #define amdgpu_ring_pad_ib(r, ib) ((r)->funcs->pad_ib((r), (ib)))
> #define amdgpu_ring_init_cond_exec(r) (r)->funcs->init_cond_exec((r))
> #define amdgpu_ring_patch_cond_exec(r,o) (r)->funcs-
> >patch_cond_exec((r),(o))
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> index a31d7ef..4e5b2f3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> @@ -210,6 +210,14 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring,
> unsigned num_ibs,
> amdgpu_ring_patch_cond_exec(ring, patch_offset);
>
> ring->current_ctx = ctx;
> +
> + /* Insert one SB at the end of DMAframe,
> + * Now only GFX8 ip need handling like this, CI won't
> + * insert one SB at this place, instead it insert double
> + * switch buffer after VM FLUSH and PIPELINE sync.
> + */
> + if (ring->funcs->emit_switch_buffer)
> + amdgpu_ring_emit_switch_buffer(ring);
> amdgpu_ring_commit(ring);
> return 0;
> }
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> index dfa2288..41a2ef1 100755
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> @@ -5936,12 +5936,6 @@ static void gfx_v8_0_ring_emit_ib_gfx(struct
> amdgpu_ring *ring, {
> u32 header, control = 0;
>
> - /* insert SWITCH_BUFFER packet before first IB in the ring frame */
> - if (ctx_switch) {
> - amdgpu_ring_write(ring,
> PACKET3(PACKET3_SWITCH_BUFFER, 0));
> - amdgpu_ring_write(ring, 0);
> - }
> -
> if (ib->flags & AMDGPU_IB_FLAG_CE)
> header = PACKET3(PACKET3_INDIRECT_BUFFER_CONST, 2);
> else
> @@ -6013,11 +6007,9 @@ static void
> gfx_v8_0_ring_emit_pipeline_sync(struct amdgpu_ring *ring)
> amdgpu_ring_write(ring, 4); /* poll interval */
>
> if (usepfp) {
> - /* synce CE with ME to prevent CE fetch CEIB before context
> switch done */
> - amdgpu_ring_write(ring,
> PACKET3(PACKET3_SWITCH_BUFFER, 0));
> - amdgpu_ring_write(ring, 0);
> - amdgpu_ring_write(ring,
> PACKET3(PACKET3_SWITCH_BUFFER, 0));
> - amdgpu_ring_write(ring, 0);
> + /* sync PFP to ME, otherwise we might get invalid PFP reads
> */
> + amdgpu_ring_write(ring, PACKET3(PACKET3_PFP_SYNC_ME,
> 0));
> + amdgpu_ring_write(ring, 0x0);
> }
> }
>
> @@ -6065,11 +6057,10 @@ static void gfx_v8_0_ring_emit_vm_flush(struct
> amdgpu_ring *ring,
> /* sync PFP to ME, otherwise we might get invalid PFP reads */
> amdgpu_ring_write(ring, PACKET3(PACKET3_PFP_SYNC_ME, 0));
> amdgpu_ring_write(ring, 0x0);
> - amdgpu_ring_write(ring,
> PACKET3(PACKET3_SWITCH_BUFFER, 0));
> - amdgpu_ring_write(ring, 0);
> - amdgpu_ring_write(ring,
> PACKET3(PACKET3_SWITCH_BUFFER, 0));
> - amdgpu_ring_write(ring, 0);
> }
> +
> + /* GFX8 emits 128 dw nop to prevent CE access VM before vm_flush
> finish */
> + amdgpu_ring_insert_nop(ring, 128);
> }
>
> static u32 gfx_v8_0_ring_get_rptr_compute(struct amdgpu_ring *ring)
> @@ -6170,6 +6161,12 @@ static void gfx_v8_0_ring_emit_wreg_kiq(struct
> amdgpu_ring *ring, u32 idx, u32 v
> amdgpu_ring_write(ring, val);
> }
>
> +static void gfx_v8_ring_emit_sb(struct amdgpu_ring *ring) {
> + amdgpu_ring_write(ring, PACKET3(PACKET3_SWITCH_BUFFER, 0));
> + amdgpu_ring_write(ring, 0);
> +}
> +
> static void gfx_v8_0_set_gfx_eop_interrupt_state(struct amdgpu_device
> *adev,
> enum
> amdgpu_interrupt_state state)
> {
> @@ -6477,6 +6474,7 @@ static const struct amdgpu_ring_funcs
> gfx_v8_0_ring_funcs_gfx = {
> .test_ib = gfx_v8_0_ring_test_ib,
> .insert_nop = amdgpu_ring_insert_nop,
> .pad_ib = amdgpu_ring_generic_pad_ib,
> + .emit_switch_buffer = gfx_v8_ring_emit_sb,
> };
>
> static const struct amdgpu_ring_funcs gfx_v8_0_ring_funcs_compute = {
> --
> 1.9.1
>
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