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