[PATCH] drm/amdgpu:implement CONTEXT_CONTROL (v3)
Bas Nieuwenhuizen
bas at basnieuwenhuizen.nl
Thu Sep 1 16:09:08 UTC 2016
On Thu, Sep 1, 2016 at 12:55 PM, Liu, Monk <Monk.Liu at amd.com> wrote:
>> Why does that makes a difference if it is seen for the first time?
>>
>> [ml] if it is presented for the first time for belonging ctx, means even current CS do not involve context switch, we still need keep the actions in preamble IB.
>> Usually if current CS is from the same cntx of previous CS, that means no ctx switch occurs, so we can skip the actions in preamble IB. but above case is the exception.
>
> Can't userspace just not set the preamble flag for the first submit with a preamble? I think that would result in the same behavior, unless having two non-preamble CE IB's in a single submit is an issue.
>
> - Bas
>
>
> [ML] I'm confused, what's your point?
So if I understand correctly, the new behavior is that the first
submit containing a preamble always executes the loads in the preamble
even if there is no context switch. The old behavior is that in that
situation the preamble would be skipped in the new situation. Why do
we want the new behavior? If the application wants the loads to
execute even without a context switch, it should not mark the IB as a
preamble with AMDGPU_IB_FLAG_PREAMBLE.
On inspecting the patch more closely I think there are more issues
with this patch.
If there is no IB with AMDGPU_IB_FLAG_PREAMBLE, then the CE_LOAD bit
always gets disabled. Furthermore if there is a CE_LOAD bit, and no
context switch the CE_LOAD bit also gets disabled for IB's without
AMDGPU_IB_FLAG_PREAMBLE.
I think this is a bad move, as there are some uses for loading CE RAM
that are not dependent on context switches, such as preloading things
into L2 cache, or switching shader uniforms in CE RAM when a different
shader gets bound. Therefore I think that the CE_LOAD bit should
always be enabled for IB's without AMDGPU_IB_FLAG_PREAMBLE.
Furthermore, with this patch the preamble IB's always get executed and
loads disabled with CONTEXT_CONTROL. As e.g. mesa uses its own
CONTEXT_CONTROL (and we can't change that for old versions of mesa)
this would override the kernel CONTEXT_CONTROL and always execute the
loads.
I also miss the CE_LOAD bit in the CONTEXT_CONTROL for gfx7. Does it
not need it?
I would prefer keeping the old system for preamble IB's and just
adding a generic CONTEXT_CONTROL that always enables the CE loads. I
don't have an opinion the non-CE loads though, as I've never found a
reason to use them.
- Bas
> With this patch, preamble_flag is not needed at all.
> Without this patch, many original assumption and logic is not correct.
> Besides, CONTEXT_CONTROL not only deals CE but also deal DE.
>
> BR Monk
>
>
> -----Original Message-----
> From: Bas Nieuwenhuizen [mailto:bas at basnieuwenhuizen.nl]
> Sent: Thursday, September 01, 2016 4:19 PM
> To: Liu, Monk <Monk.Liu at amd.com>
> Cc: Christian König <deathsimple at vodafone.de>; amd-gfx at lists.freedesktop.org
> Subject: Re: [PATCH] drm/amdgpu:implement CONTEXT_CONTROL (v3)
>
> On Thu, Sep 1, 2016 at 9:37 AM, Liu, Monk <Monk.Liu at amd.com> wrote:
>>
>>
>> -----Original Message-----
>> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
>> Of Christian K?nig
>> Sent: Wednesday, August 31, 2016 7:53 PM
>> To: Liu, Monk <Monk.Liu at amd.com>; amd-gfx at lists.freedesktop.org
>> Subject: Re: [PATCH] drm/amdgpu:implement CONTEXT_CONTROL (v3)
>>
>> Looks good to me in general, a few nit picks and sugegstions below.
>>
>> Am 31.08.2016 um 05:49 schrieb Monk Liu:
>>> v1:
>>> for gfx8, use CONTEXT_CONTROL package to dynamically skip preamble
>>> CEIB and other load_xxx command in sequence.
>>>
>>> v2:
>>> support GFX7 as well, and bump up version.
>>> remove cntxcntl in compute ring funcs because CPC doesn't support
>>> this packet.
>>>
>>> v3: fix reduntant judgement in cntxcntl.
>>>
>>> Change-Id: I4b87ca84ea8c11ba4f7fb4c0e8a5be537ccde851
>>> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
>>>
>>> Change-Id: I5d24c1bb5c14190ce4adeb6a331ee3d92b3d5c83
>>> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
>>
>> Only one signed of by line is enough and remove the change-ids.
>>
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 9 +++++++++
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 12 ++++++++++++
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 3 ++-
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c | 16 +++++++++-------
>>> drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c | 20 ++++++++++++++++++++
>>> drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c | 30 ++++++++++++++++++++++++++++++
>>> 6 files changed, 82 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> index 1254410..0de5f08 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> @@ -321,6 +321,7 @@ struct amdgpu_ring_funcs {
>>> void (*begin_use)(struct amdgpu_ring *ring);
>>> void (*end_use)(struct amdgpu_ring *ring);
>>> void (*emit_switch_buffer) (struct amdgpu_ring *ring);
>>> + void (*emit_cntxcntl) (struct amdgpu_ring *ring, uint32_t
>>> + flags);
>>> };
>>>
>>> /*
>>> @@ -965,6 +966,7 @@ struct amdgpu_ctx {
>>> spinlock_t ring_lock;
>>> struct fence **fences;
>>> struct amdgpu_ctx_ring rings[AMDGPU_MAX_RINGS];
>>> + bool preamble_presented;
>>> };
>>>
>>> struct amdgpu_ctx_mgr {
>>> @@ -1227,8 +1229,13 @@ struct amdgpu_cs_parser {
>>>
>>> /* user fence */
>>> struct amdgpu_bo_list_entry uf_entry;
>>> + bool preamble_present; /* True means this command submit
>>> +involves a preamble IB */
>>
>> We only need this in amdgpu_cs_ib_fill() don't we? See below as well.
>>
>> [ML] seems good advice
>>
>>> };
>>>
>>> +#define PREAMBLE_IB_PRESENT (1 << 0) /* bit set means command submit involves a preamble IB */
>>> +#define PREAMBLE_IB_PRESENT_FIRST (1 << 1) /* bit set means preamble IB is first presented in belonging context */
>>
>> Why does that makes a difference if it is seen for the first time?
>>
>> [ml] if it is presented for the first time for belonging ctx, means even current CS do not involve context switch, we still need keep the actions in preamble IB.
>> Usually if current CS is from the same cntx of previous CS, that means no ctx switch occurs, so we can skip the actions in preamble IB. but above case is the exception.
>
> Can't userspace just not set the preamble flag for the first submit with a preamble? I think that would result in the same behavior, unless having two non-preamble CE IB's in a single submit is an issue.
>
> - Bas
>
>>
>>> +#define HAVE_CTX_SWITCH (1 << 2) /* bit set means context switch occured */
>>> +
>>> struct amdgpu_job {
>>> struct amd_sched_job base;
>>> struct amdgpu_device *adev;
>>> @@ -1237,6 +1244,7 @@ struct amdgpu_job {
>>> struct amdgpu_sync sync;
>>> struct amdgpu_ib *ibs;
>>> struct fence *fence; /* the hw fence */
>>> + uint32_t preamble_status;
>>> uint32_t num_ibs;
>>> void *owner;
>>> uint64_t fence_ctx; /* the fence_context this job uses */
>>> @@ -2264,6 +2272,7 @@ amdgpu_get_sdma_instance(struct amdgpu_ring *ring)
>>> #define amdgpu_ring_emit_hdp_flush(r) (r)->funcs->emit_hdp_flush((r))
>>> #define amdgpu_ring_emit_hdp_invalidate(r) (r)->funcs->emit_hdp_invalidate((r))
>>> #define amdgpu_ring_emit_switch_buffer(r)
>>> (r)->funcs->emit_switch_buffer((r))
>>> +#define amdgpu_ring_emit_cntxcntl(r, d)
>>> +(r)->funcs->emit_cntxcntl((r), (d))
>>> #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_cs.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>> index 2d4e005..6d8c050 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>>> @@ -792,6 +792,9 @@ static int amdgpu_cs_ib_fill(struct amdgpu_device *adev,
>>> if (r)
>>> return r;
>>>
>>> + if (ib->flags & AMDGPU_IB_FLAG_PREAMBLE)
>>> + parser->preamble_present = true;
>>> +
>>> if (parser->job->ring && parser->job->ring != ring)
>>> return -EINVAL;
>>>
>>> @@ -930,6 +933,12 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
>>> return r;
>>> }
>>>
>>> + if (p->preamble_present) {
>>> + job->preamble_status |= PREAMBLE_IB_PRESENT;
>>> + if (!p->ctx->preamble_presented)
>>> + job->preamble_status |= PREAMBLE_IB_PRESENT_FIRST;
>>> + }
>>> +
>>
>> Better move this to the end of amdgpu_cs_ib_fill() where we allocate the IBs as well.
>> [ML] okay, good change.
>>
>>
>>
>>> job->owner = p->filp;
>>> job->fence_ctx = entity->fence_context;
>>> p->fence = fence_get(&job->base.s_fence->finished);
>>> @@ -940,6 +949,9 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
>>> trace_amdgpu_cs_ioctl(job);
>>> amd_sched_entity_push_job(&job->base);
>>>
>>> + if (p->preamble_present)
>>> + p->ctx->preamble_presented = true;
>>> +
>>> return 0;
>>> }
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>> index 56c85e6..44db0ab 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>> @@ -55,9 +55,10 @@
>>> * - 3.3.0 - Add VM support for UVD on supported hardware.
>>> * - 3.4.0 - Add AMDGPU_INFO_NUM_EVICTIONS.
>>> * - 3.5.0 - Add support for new UVD_NO_OP register.
>>> + * - 3.6.0 - UMD doesn't/shouldn't need to use CONTEXT_CONTROL in
>>> + IB, KMD should do it
>>> */
>>> #define KMS_DRIVER_MAJOR 3
>>> -#define KMS_DRIVER_MINOR 5
>>> +#define KMS_DRIVER_MINOR 6
>>> #define KMS_DRIVER_PATCHLEVEL 0
>>>
>>> int amdgpu_vram_limit = 0;
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
>>> index 04263f0..b12b5ba 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
>>> @@ -121,10 +121,11 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
>>> {
>>> struct amdgpu_device *adev = ring->adev;
>>> struct amdgpu_ib *ib = &ibs[0];
>>> - bool skip_preamble, need_ctx_switch;
>>> + bool need_ctx_switch;
>>> unsigned patch_offset = ~0;
>>> struct amdgpu_vm *vm;
>>> uint64_t fence_ctx;
>>> + uint32_t status = 0;
>>>
>>> unsigned i;
>>> int r = 0;
>>> @@ -174,15 +175,16 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
>>> /* always set cond_exec_polling to CONTINUE */
>>> *ring->cond_exe_cpu_addr = 1;
>>>
>>> - skip_preamble = ring->current_ctx == fence_ctx;
>>> need_ctx_switch = ring->current_ctx != fence_ctx;
>>> + if (job && ring->funcs->emit_cntxcntl) {
>>> + if (need_ctx_switch)
>>> + status |= HAVE_CTX_SWITCH;
>>> + status |= job->preamble_status;
>>> + amdgpu_ring_emit_cntxcntl(ring, status);
>>> + }
>>> +
>>> for (i = 0; i < num_ibs; ++i) {
>>> ib = &ibs[i];
>>> -
>>> - /* drop preamble IBs if we don't have a context switch */
>>> - if ((ib->flags & AMDGPU_IB_FLAG_PREAMBLE) && skip_preamble)
>>> - continue;
>>> -
>>
>> Would be nice to keep this functionality for cases where we don't support emit_cntxcntl (e.g. SI?).
>> [ML] SI support CONTEXT_CONTROL as well, and the package structure is exactly the same as CI.
>>
>>> amdgpu_ring_emit_ib(ring, ib, job ? job->vm_id : 0,
>>> need_ctx_switch);
>>> need_ctx_switch = false; diff --git
>>> a/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
>>> b/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
>>> index f055d49..0d5addb 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v7_0.c
>>> @@ -2096,6 +2096,25 @@ static void gfx_v7_0_ring_emit_ib_compute(struct amdgpu_ring *ring,
>>> amdgpu_ring_write(ring, control);
>>> }
>>>
>>> +static void gfx_v7_ring_emit_cntxcntl(struct amdgpu_ring *ring,
>>> +uint32_t flags) {
>>> + uint32_t dw2 = 0;
>>> +
>>> + dw2 |= 0x80000000; /* set load_enable otherwise this package is just NOPs */
>>> + if (flags & HAVE_CTX_SWITCH) {
>>> + /* set load_global_config & load_global_uconfig */
>>> + dw2 |= 0x8001;
>>> + /* set load_cs_sh_regs */
>>> + dw2 |= 0x01000000;
>>> + /* set load_per_context_state & load_gfx_sh_regs */
>>> + dw2 |= 0x10002;
>>
>> Better define some constants for those.
>>
>> [ML] I'll leave it to other guys when doing cleanups, a little hurry for other jobs now ...
>>
>> Regards,
>> Christian.
>>
>>> + }
>>> +
>>> + amdgpu_ring_write(ring, PACKET3(PACKET3_CONTEXT_CONTROL, 1));
>>> + amdgpu_ring_write(ring, dw2);
>>> + amdgpu_ring_write(ring, 0);
>>> +}
>>> +
>>> /**
>>> * gfx_v7_0_ring_test_ib - basic ring IB test
>>> *
>>> @@ -4929,6 +4948,7 @@ static const struct amdgpu_ring_funcs gfx_v7_0_ring_funcs_gfx = {
>>> .test_ib = gfx_v7_0_ring_test_ib,
>>> .insert_nop = amdgpu_ring_insert_nop,
>>> .pad_ib = amdgpu_ring_generic_pad_ib,
>>> + .emit_cntxcntl = gfx_v7_ring_emit_cntxcntl,
>>> };
>>>
>>> static const struct amdgpu_ring_funcs gfx_v7_0_ring_funcs_compute =
>>> { diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
>>> b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
>>> index 8ba8e42..73f6ffa 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
>>> @@ -6085,6 +6085,35 @@ static void gfx_v8_ring_emit_sb(struct amdgpu_ring *ring)
>>> amdgpu_ring_write(ring, 0);
>>> }
>>>
>>> +static void gfx_v8_ring_emit_cntxcntl(struct amdgpu_ring *ring,
>>> +uint32_t flags) {
>>> + uint32_t dw2 = 0;
>>> +
>>> + dw2 |= 0x80000000; /* set load_enable otherwise this package is just NOPs */
>>> + if (flags & HAVE_CTX_SWITCH) {
>>> + /* set load_global_config & load_global_uconfig */
>>> + dw2 |= 0x8001;
>>> + /* set load_cs_sh_regs */
>>> + dw2 |= 0x01000000;
>>> + /* set load_per_context_state & load_gfx_sh_regs for GFX */
>>> + dw2 |= 0x10002;
>>> +
>>> + /* set load_ce_ram if preamble presented */
>>> + if (PREAMBLE_IB_PRESENT & flags)
>>> + dw2 |= 0x10000000;
>>> + } else {
>>> + /* still load_ce_ram if this is the first time preamble presented
>>> + * although there is no context switch happens.
>>> + */
>>> + if (PREAMBLE_IB_PRESENT_FIRST & flags)
>>> + dw2 |= 0x10000000;
>>> + }
>>> +
>>> + amdgpu_ring_write(ring, PACKET3(PACKET3_CONTEXT_CONTROL, 1));
>>> + amdgpu_ring_write(ring, dw2);
>>> + amdgpu_ring_write(ring, 0);
>>> +}
>>> +
>>> static void gfx_v8_0_set_gfx_eop_interrupt_state(struct amdgpu_device *adev,
>>> enum amdgpu_interrupt_state state)
>>> {
>>> @@ -6267,6 +6296,7 @@ static const struct amdgpu_ring_funcs gfx_v8_0_ring_funcs_gfx = {
>>> .insert_nop = amdgpu_ring_insert_nop,
>>> .pad_ib = amdgpu_ring_generic_pad_ib,
>>> .emit_switch_buffer = gfx_v8_ring_emit_sb,
>>> + .emit_cntxcntl = gfx_v8_ring_emit_cntxcntl,
>>> };
>>>
>>> static const struct amdgpu_ring_funcs gfx_v8_0_ring_funcs_compute =
>>> {
>>
>>
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