On Mon, Sep 01, 2014 at 05:41:30PM +0200, Philipp Lutz wrote: > Have you looked into setting a RTPRIO for the SPI worker threads > (spi_init_queue() in spi.c)? As far as I see hardly any SPI > hardware-dependent driver sets the "rt" property in the respective > spi_master struct, so that the main SPI driver (spi.c) will not use a RT > priority, which will be MAX_RT_PRIO - 1. Sort of. I was unaware of the "rt" property so I never tried setting it on the kernel side. However, I did run into the idea of using "chrt" on the kernel tasks [spi1] and [irq/99-spi-s3c6]. This improved things somewhat, but this plus eliminating DMA acquistion still left me with some 800+us latencies that I didn't want. (it may have also helped somewhat to to use cpuset to bind these tasks to the same CPU where my realtime task runs--the U3 is a 4-core chip, and linuxcnc binds to the last CPU by default) Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
