setitimer lowlatency-2.2.13-A1 questions

William Montgomery (william@opinicus.com)
Mon, 6 Dec 1999 10:07:45 -0500 (EST)

I tried using setitimer as a scheduling source for lowlatency testing
with generally good results. I left my test running over the weekend
and found some large latencies had occurred. It appears that since
the signal generation occurs in timer_bh, it is possible for a user
task to run between when the timer_interrupt occurs and when timer_bh
runs (~2msec in my case).

Is it correct to assume that the only _safe_ timing source for
lowlatency is the rtc using the fasync method?

Also is it valid to assume that no interrupt driven timing source
is safe from the psaux disabling interrupts for up to 3msec?

Wm

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