On Wed, Feb 15, 2017 at 7:12 PM, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote: > On 2017-02-05 19:11:01 [+0200], Ran Shalit wrote: >> Hello, > Hi, > >> We made some testing on out cpu, installed with 4.1.15-rt17 kernel, >> and we observed significant difference in latency between posic to >> non-posix cyclictest benchmark. >> >> with non posix we reach max ~50usec >> while with posix we reach max ~170usec >> >> On checking the exaples in cyclic test wiki, it seems that the >> difference should not be that big : >> https://rt.wiki.kernel.org/index.php/Cyclictest >> >> What is the reason for such difference in behaviour ? >> Does it mean we better use non-posix timer in application ? > As written in the other thread (regarding posix-timer): > I tested today v4.9-RT and didn't notice such high spikes between > clock_nanosleep and the posix timer. You have the consider that the > wakeup happens from ktimersoftirq so you have one additional context > switch here. > I general the clock_nansleep interface should be preferred if possible > to avoid that ctx switch. > I understand, Thank you a lot. Ran > Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
