From: "Michel Dänzer" <michel@daenzer.net>
To: "Christian König" <deathsimple@vodafone.de>
Cc: mesa-dev@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 2/2] r600g/radeonsi: Prefer VRAM for CPU -> GPU streaming buffers
Date: Thu, 31 Jul 2014 18:57:57 +0900 [thread overview]
Message-ID: <53DA1325.3020301@daenzer.net> (raw)
In-Reply-To: <53DA11DC.3060601@vodafone.de>
On 31.07.2014 18:52, Christian König wrote:
> Am 31.07.2014 um 11:43 schrieb Michel Dänzer:
>> From: Michel Dänzer <michel.daenzer@amd.com>
>>
>> Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
>
> At least for PIPE_USAGE_STREAM buffers that's a bad idea, cause they are
> used by VDPAU to read back to data to a CPU buffer and that's really
> slow from VRAM.
From src/gallium/docs/source/screen.rst:
* ``PIPE_USAGE_DEFAULT``: Optimized for fast GPU access.
* ``PIPE_USAGE_IMMUTABLE``: Optimized for fast GPU access and the resource is
not expected to be mapped or changed (even by the GPU) after the first upload.
* ``PIPE_USAGE_DYNAMIC``: Expect frequent write-only CPU access. What is
uploaded is expected to be used at least several times by the GPU.
* ``PIPE_USAGE_STREAM``: Expect frequent write-only CPU access. What is
uploaded is expected to be used only once by the GPU.
* ``PIPE_USAGE_STAGING``: Optimized for fast CPU access.
That reads to me like only PIPE_USAGE_STAGING is expected to provide fast
CPU reads.
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Mesa and X developer
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next prev parent reply other threads:[~2014-07-31 9:57 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-31 9:43 [PATCH 0/2] radeon: Allow streaming data from CPU to GPU via VRAM Michel Dänzer
2014-07-31 9:43 ` [PATCH 1/2] drm/radeon: s/ioctl_wait_idle/mmio_hpd_flush/ Michel Dänzer
2014-07-31 18:39 ` Alex Deucher
2014-07-31 9:43 ` [PATCH 2/2] drm/radeon: Always flush the HDP cache before submitting a CS to the GPU Michel Dänzer
2014-07-31 9:43 ` [PATCH 1/2] r600g/radeonsi: Reduce or even drop special treatment of persistent mappings Michel Dänzer
2014-07-31 17:36 ` Marek Olšák
2014-07-31 9:43 ` [PATCH 2/2] r600g/radeonsi: Prefer VRAM for CPU -> GPU streaming buffers Michel Dänzer
2014-07-31 9:52 ` Christian König
2014-07-31 9:57 ` Michel Dänzer [this message]
2014-07-31 10:06 ` Christian König
2014-07-31 17:40 ` Marek Olšák
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