On 08/12/2015 01:00 AM, Xander Huff wrote: > The driver currently registers a pair of irq handlers using > request_threaded_irq(), however the synchronization mechanism between the > hardirq and the threadedirq handler is a regular spinlock. > > Unfortunately, this breaks PREEMPT_RT builds, where a spinlock can sleep, > and is thus not able to be acquired from a hardirq handler. This patch gets > rid of the threaded handler and pushes all interrupt handling into the > hardirq context, and uses request_irq(). > > To validate that this change has no impact on RT performance, here are > cyclictest values with no processes running: > > $ sudo cyclictest -S -m -p 98 > # /dev/cpu_dma_latency set to 0us > policy: fifo: loadavg: 0.00 0.01 0.05 1/174 2539 > T: 0 ( 1405) P:98 I:1000 C:167010520 Min: 9 Act: 12 Avg: 12 Max: 75 > T: 1 ( 1862) P:98 I:1500 C:111340339 Min: 9 Act: 12 Avg: 12 Max: 73 > > Then, all xadc raw handles were accessed in a continuous loop via > /sys/bus/iio/devices/iio:device0: > > $ sudo cyclictest -S -m -p 98 > # /dev/cpu_dma_latency set to 0us > policy: fifo: loadavg: 7.84 7.70 7.63 3/182 4260 > T: 0 ( 2559) P:98 I:1000 C:241557018 Min: 11 Act: 18 Avg: 21 Max: 74 > T: 1 ( 2560) P:98 I:1500 C:161038006 Min: 10 Act: 21 Avg: 20 Max: 73 > > Signed-off-by: Xander Huff <xander.huff@xxxxxx> Looks good, thanks. Acked-by: Lars-Peter Clausen <lars@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
