Messages in this thread | | | Date | Tue, 28 Jan 2003 21:39:54 +0000 | From | Jamie Lokier <> | Subject | Re: bug in select() (was Re: {sys_,/dev/}epoll waiting timeout) |
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Mark Mielke wrote: > On Tue, Jan 28, 2003 at 09:45:00AM +0000, Jamie Lokier wrote: > > Davide Libenzi wrote: > > > ( if Tms > 0 ) > > Which is unfortunate, because that doesn't allow for a value of Tms == > > 0 which is needed when you want to sleep and wake up on every jiffie > > on systems where HZ >= 1000. Tms == 0 is taken already, to mean do > > not wait at all. > > To some degree, isn't this the equivalent of yield()?
No. If you want a process to wake every HZ tick, do a little work and then sleep again, yield() won't do that.
If HZ >= 1000, you simply can't use Linux poll() to do that; you have to use select(). (Or epoll_wait()).
Even if select() is changed to do double-rounding-up like poll(), it will still do this because select() times have microsecond granularity.
-- Jamie
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