Messages in this thread | | | From | Kari Hameenaho <> | Subject | Change of setitimer() handling in 2.6.0-testX against 2.5.69 (and 2.4.x) ? | Date | Tue, 16 Dec 2003 23:49:46 +0200 |
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There was previously a linux-kernel mailing list thread about scheduling degration (actually change of nanosleep timeout handling). I am not so interrested in nanosleep, but I do have an application using setitimer().
I did some test code and noticed that it_interval handling in setitimer(ITIMER_REAL ...) has also changed:
- machine is otherwise idle, SMP, threads RT priority or not - SIGALRM comes in average every 1 ms in 2.5.x (and 1000 Hz patched 2.4.x) - SIGALRM comes in average every 2 ms in 2.6.0-test11 (also 2.6.0-test8)
Setting of the timer:
it.it_value.tv_sec = 0; it.it_value.tv_usec = 1000; it.it_interval.tv_sec = 0; it.it_interval.tv_usec = 1000; setitimer(ITIMER_REAL,&it,NULL);
Of course when asked for longer timeouts, the 1 ms difference remains.
Looking at the man page, this also seems to be OK (if this interval is interpreted as a timeout, which can be longer but not shorter than expected).
However, building a timebase for an application by setitimer() has definitely changed, so every code relying on the interval really being averaged correctly is now a little bit broken.
Is this intended or some side effect of other recent changes ?
-- Kari Hämeenaho - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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