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* [PATCH v4 0/2] media: usb: pwc: Don't use coherent DMA buffers for ISO transfer
@ 2018-08-09 18:11 Matwey V. Kornilov
  2018-08-09 18:11 ` [PATCH v4 1/2] media: usb: pwc: Introduce TRACE_EVENTs for pwc_isoc_handler() Matwey V. Kornilov
                   ` (2 more replies)
  0 siblings, 3 replies; 15+ messages in thread
From: Matwey V. Kornilov @ 2018-08-09 18:11 UTC (permalink / raw)
  To: linux-media, linux-kernel
  Cc: Matwey V. Kornilov, tfiga, laurent.pinchart, matwey, stern,
	ezequiel, hdegoede, hverkuil, mchehab, rostedt, mingo, isely,
	bhumirks, colin.king, kieran.bingham, keiichiw

From: "Matwey V. Kornilov" <matwey.kornilov@gmail.com>

DMA cocherency slows the transfer down on systems without hardware coherent
DMA. In order to demontrate this we introduce performance measurement
facilities in patch 1 and fix the performance issue in patch 2 in order to
obtain 4 times speedup.

Changes since v3:
 * fix scripts/checkpatch.pl errors
 * use __string to store name in trace events

Changes since v2:
 * use dma_sync_single_for_cpu() to achive better performance
 * remeasured performance

Changes since v1:
 * trace_pwc_handler_exit() call moved to proper place
 * detailed description added for commit 1
 * additional output added to trace to track separate frames


Matwey V. Kornilov (2):
  media: usb: pwc: Introduce TRACE_EVENTs for pwc_isoc_handler()
  media: usb: pwc: Don't use coherent DMA buffers for ISO transfer

 drivers/media/usb/pwc/pwc-if.c | 63 ++++++++++++++++++++++++++++++++--------
 include/trace/events/pwc.h     | 65 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 116 insertions(+), 12 deletions(-)
 create mode 100644 include/trace/events/pwc.h

-- 
2.16.4


^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2018-09-20 14:28 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-08-09 18:11 [PATCH v4 0/2] media: usb: pwc: Don't use coherent DMA buffers for ISO transfer Matwey V. Kornilov
2018-08-09 18:11 ` [PATCH v4 1/2] media: usb: pwc: Introduce TRACE_EVENTs for pwc_isoc_handler() Matwey V. Kornilov
2018-08-09 18:26   ` Steven Rostedt
2018-08-09 18:39     ` Matwey V. Kornilov
2018-08-09 18:11 ` [PATCH v4 2/2] media: usb: pwc: Don't use coherent DMA buffers for ISO transfer Matwey V. Kornilov
2018-08-10  8:53   ` Laurent Pinchart
2018-08-10  9:38     ` Matwey V. Kornilov
2018-08-10  9:49       ` Laurent Pinchart
2018-08-10 14:27         ` Alan Stern
2018-08-17 17:44           ` Matwey V. Kornilov
2018-08-21  8:36             ` Matwey V. Kornilov
2018-09-20 13:55           ` Ezequiel Garcia
2018-09-20 14:28             ` Alan Stern
2018-08-09 19:31 ` [PATCH v4 0/2] " Linus Torvalds
2018-08-10  8:28   ` Matwey V. Kornilov

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