On Wed, Nov 4, 2009 at 12:01 AM, Rajat Jain <Rajat.Jain@xxxxxxxxxxxx> wrote: > Hi, > >> I find something interesting; kernel has msleep, but it >> doesn't have usleep. >> Does that mean the minimum time kernel can react is msecond >> instead of usecond? >> so if users want to count useconds, they have to do the busy waiting, >> execute some looping assembly instructions? > > You are roughly right. If you don't want to busy loop (udelay / mdelay), then you will have to sleep. The granularity of this sleep depends on how frequently the timer interrupt ticks (HZ). Thus if HZ is 1000, then you cannot sleep for a period less than 1 msec. I thought hrtimers allow higher-precision wakeups these days? Of course, if you only want to sleep for a few microseconds, the context switch might take longer than you want to sleep... -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
