[Mesa-dev] [PATCH 1/7] nvc0: reduce the number of PUSH_SPACE in draw path

[Samuel Pitoiset]

On 11/07/2016 04:32 AM, Ilia Mirkin wrote:
> On Wed, Oct 26, 2016 at 4:14 AM, Samuel Pitoiset
> <samuel.pitoiset at gmail.com> wrote:
>>
>>
>> On 10/25/2016 09:49 PM, Ilia Mirkin wrote:
>>>
>>> What if instance_count = 1M? (It can happen.)
>>
>>
>> We allocate a giant space in the pushbuf in one shot. Well, anyways this is
>> not the optimization of the year, so I can drop it. :-)
>
> There are limits to pushbuf sizes. Either drop it, or batch the
> instance draws. There's really very limited advantage to doing it this
> way though, since PUSH_SPACE is a no-op unless the pushbuf is full.

Yes, it's really minor, I will discard it.

>
>>
>>
>>>
>>> On Tue, Oct 25, 2016 at 3:41 PM, Samuel Pitoiset
>>> <samuel.pitoiset at gmail.com> wrote:
>>>>
>>>> This might help CPU-bounds applications but should not have
>>>> any real effects for GPU-bounds ones.
>>>>
>>>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>>>> ---
>>>>  src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c | 8 +++-----
>>>>  1 file changed, 3 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c
>>>> b/src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c
>>>> index 69ca091..bc4ab9e 100644
>>>> --- a/src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c
>>>> +++ b/src/gallium/drivers/nouveau/nvc0/nvc0_vbo.c
>>>> @@ -598,8 +598,8 @@ nvc0_draw_arrays(struct nvc0_context *nvc0,
>>>>
>>>>     prim = nvc0_prim_gl(mode);
>>>>
>>>> +   PUSH_SPACE(push, 6 * instance_count);
>>>>     while (instance_count--) {
>>>> -      PUSH_SPACE(push, 6);
>>>>        BEGIN_NVC0(push, NVC0_3D(VERTEX_BEGIN_GL), 1);
>>>>        PUSH_DATA (push, prim);
>>>>        BEGIN_NVC0(push, NVC0_3D(VERTEX_BUFFER_FIRST), 2);
>>>> @@ -730,10 +730,9 @@ nvc0_draw_elements(struct nvc0_context *nvc0, bool
>>>> shorten,
>>>>     }
>>>>
>>>>     if (nvc0->idxbuf.buffer) {
>>>> -      PUSH_SPACE(push, 1);
>>>> +      PUSH_SPACE(push, 1 + 7 * instance_count);
>>>>        IMMED_NVC0(push, NVC0_3D(VERTEX_BEGIN_GL), prim);
>>>>        do {
>>>> -         PUSH_SPACE(push, 7);
>>>>           BEGIN_NVC0(push, NVC0_3D(INDEX_BATCH_FIRST), 2);
>>>>           PUSH_DATA (push, start);
>>>>           PUSH_DATA (push, count);
>>>> @@ -747,8 +746,8 @@ nvc0_draw_elements(struct nvc0_context *nvc0, bool
>>>> shorten,
>>>>     } else {
>>>>        const void *data = nvc0->idxbuf.user_buffer;
>>>>
>>>> +      PUSH_SPACE(push, 3 * instance_count);
>>>>        while (instance_count--) {
>>>> -         PUSH_SPACE(push, 2);
>>>>           BEGIN_NVC0(push, NVC0_3D(VERTEX_BEGIN_GL), 1);
>>>>           PUSH_DATA (push, prim);
>>>>           switch (index_size) {
>>>> @@ -768,7 +767,6 @@ nvc0_draw_elements(struct nvc0_context *nvc0, bool
>>>> shorten,
>>>>              assert(0);
>>>>              return;
>>>>           }
>>>> -         PUSH_SPACE(push, 1);
>>>>           IMMED_NVC0(push, NVC0_3D(VERTEX_END_GL), 0);
>>>>
>>>>           prim |= NVC0_3D_VERTEX_BEGIN_GL_INSTANCE_NEXT;
>>>> --
>>>> 2.10.1
>>>>
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>>>> mesa-dev at lists.freedesktop.org
>>>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>>
>>
>> --
>> -Samuel