01270f905e
Replace SNDRV_DMA_TYPE_DEV by SNDRV_DMA_TYPE_NONCOHERENT for pcm
buffer allocation. We measured about 18x performance improvement
when accessing the snd_pcm_mmap() buffer from userspace.
Eg: aarch64 with internal speaker
==
SNDRV_DMA_TYPE_DEV
frames_per_second=66.4557M/s
max_time_per_4096_frames=106.094u
time_per_4096_frames=61.6351us
SNDRV_DMA_TYPE_NONCOHERENT
frames_per_second=1028.58M/s
max_time_per_4096_frames=20.312u
time_per_4096_frames=3.98221us
Signed-off-by: Judy Hsiao <judyhsiao@chromium.org>
Link: https://lore.kernel.org/r/20221208084200.2136311-1-judyhsiao@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.