Re: [PATCH libdrm] amdgpu: add a faster BO list API

[Christian König <ckoenig.leichtzumerken@xxxxxxxxx>]

Am 09.01.19 um 17:14 schrieb Marek Olšák:

On Wed, Jan 9, 2019 at 8:09 AM Christian König <ckoenig.leichtzumerken@xxxxxxxxx> wrote:

Am 09.01.19 um 13:36 schrieb Marek Olšák:

On Wed, Jan 9, 2019, 5:28 AM Christian König <ckoenig.leichtzumerken@xxxxxxxxx wrote:

Looks good, but I'm wondering what's the actual improvement?

No malloc calls and 1 less for loop copying the bo list.

Yeah, but didn't we want to get completely rid of the bo list?

If we have multiple IBs (e.g. gfx + compute) that share a BO list, I think it's faster to send the BO list to the kernel only once.

That's not really faster.

The only thing we safe us is a single loop over all BOs to lockup the handle into a pointer and that is only a tiny fraction of the overhead.

The majority of the overhead is locking the BOs and reserving space for the submission.

What could really help here is to submit gfx+comput together in just one CS IOCTL. This way we would need the locking and space reservation only once.

It's a bit of work in the kernel side, but certainly doable.

Christian.

Marek

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