Sound Tweak Rpi4

[Tim Curtis]

What would be nice is to see a time stamped trace of sample frames within the OS showing some that sort of timing issue, frame loss, etc actually exists. Then it could be analyzed to see what's causing the problem.

Anyway, my point in posting about latency is to provide info from an engineers point of view which leans heavily on testing and analysis :-)

The 32 bit kernels are compiled with CONFIG_PREEMPT_VOLUNTARY=y

Code:

pi@rp3:~ $ uname -a
Linux rp3 5.4.49-v7+ #1323 SMP Fri Jun 26 14:34:26 BST 2020 armv7l GNU/Linux
pi@rp3:~ $ sudo modprobe configs
pi@rp3:~ $ zcat /proc/config.gz | grep PREEMPT
# CONFIG_PREEMPT_NONE is not set
CONFIG_PREEMPT_VOLUNTARY=y
# CONFIG_PREEMPT is not set
CONFIG_PREEMPTIRQ_TRACEPOINTS=y
# CONFIG_PREEMPTIRQ_EVENTS is not set
# CONFIG_PREEMPTIRQ_DELAY_TEST is not set

The 64-bit kernels are compiled with CONFIG_PREEMPT=y

Code:

pi@rp3:~ $ uname -a
Linux rp3 5.4.49-v8+ #1323 SMP PREEMPT Fri Jun 26 14:47:11 BST 2020 aarch64 GNU/Linux
pi@rp3:~ $ sudo modprobe configs
pi@rp3:~ $ zcat /proc/config.gz | grep PREEMPT
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
CONFIG_PREEMPT=y
CONFIG_PREEMPT_COUNT=y
CONFIG_PREEMPTION=y
CONFIG_PREEMPT_RCU=y
CONFIG_PREEMPT_NOTIFIERS=y
CONFIG_DEBUG_PREEMPT=y
CONFIG_PREEMPTIRQ_TRACEPOINTS=y
# CONFIG_PREEMPTIRQ_EVENTS is not set
# CONFIG_PREEMPT_TRACER is not set
# CONFIG_PREEMPTIRQ_DELAY_TEST is not set