6 May
2005
6 May
'05
4:17 p.m.
On Fri, 2005-05-06 at 14:30 +0200, Benno Senoner wrote:
Paul Davis wrote:
Not anymore. From man 2 nanosleep:
Old behaviour
In order to support applications requiring much more precise
pauses (e.g., in order to control some time-critical hardware),
nanosleep would handle pauses of up
to 2 ms by busy waiting with microsecond precision when called
from a process scheduled under a real-time policy like SCHED_FIFO or
SCHED_RR. This special
extension was removed in kernel 2.5.39, hence is still present in
current 2.4 kernels, but not in 2.6 kernels.
Lee
usleep (2) is the canonical high resolution sleep
function on POSIX
(although nanosleep(2) is a close cousin). the resolution is limited
by the system timer interrupt frequency, which is typically either
100Hz (2.4 and older kernels) or 1kHz (2.6 kernels)
Right,
nanosleep() might be a bit more precise than usleep() but for low sleep
values ( AFAIK < 2msec ) it
busywaits when you run your app SCHED_FIFO which in the case of
sustained streams of low sleep values
could chew up all the CPU, not idea for real time audio apps.