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Linux kernel stable tree
68d0c3311e
Replace the urb buffers allocation to use the noncontiguous API. This improves performance on ARM platforms where DMA coherent allocations produce uncached mappings. Note that the noncontiguous API requires the driver to handle synchronization. This commit is similar to this one for the uvc driver: https://lkml.org/lkml/2021/3/12/1506 Performance tests on rock-pi4 (Arm64) shows about 15x improvements: == DMA NONCONTIGUOUS == total durations: 20.63678480 sec urb processing durations: 0.286864889 sec uS/qty: 286864/2508 avg: 114.379 min: 0.583 max: 155.461 (uS) FPS: 24.92 lost: 0 done: 500 raw decode speed: 11.603 Gbits/s bytes 414831228.000 bytes/urb: 165403 == DMA COHERENT == total durations: 20.73551767 sec urb processing durations: 4.541559160 sec uS/qty: 4541559/2509 avg: 1810.107 min: 0.583 max: 2113.163 (uS) FPS: 24.90 lost: 0 done: 500 raw decode speed: 730.738 Mbits/s bytes 414785444.000 bytes/urb: 165319 Performance tests on x86 laptop show no significant difference: == DMA NONCONTIGUOUS == total durations: 20.220590102 sec urb processing durations: 0.63021818 sec uS/qty: 63021/2512 avg: 25.088 min: 0.138 max: 146.750 (uS) FPS: 24.72 lost: 0 done: 500 raw decode speed: 52.751 Gbits/s bytes 415421032.000 bytes/urb: 165374 == DMA COHERENT == total durations: 20.220475614 sec urb processing durations: 0.64751972 sec uS/qty: 64751/2512 avg: 25.777 min: 0.168 max: 132.250 (uS) FPS: 24.72 lost: 0 done: 500 raw decode speed: 51.927 Gbits/s bytes 415422794.000 bytes/urb: 165375 [hverkuil: incorporated Ezequiel's suggestions from his review] Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com> Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org> |
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| certs | ||
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| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.