Date: Sat, 18 Feb 2012 21:05:52 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: freebsd-hackers@FreeBSD.org Subject: callouts precision Message-ID: <4F3FF690.5050600@FreeBSD.org>
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Just want to double-check myself. It seems that currently, thanks to event timers, we mostly should be able to schedule a hardware timer to fire at almost arbitrary moment with very fine precision. OTOH, our callout subsystem still seems to be completely tick oriented in the sense that all timeouts are specified and kept in ticks. As a result, it's impossible to use e.g. nanosleep(2) with a precision better than HZ. How deeply ticks are ingrained into callout(9)? Are they used only as a measure of time? Or are there any dependencies on them being integers, like for indexing, etc? In other words, how hard it would be to replace ticks with e.g. bintime as an internal representation of time in callout(9) [leaving interfaces alone for the start]? Is it easier to retrofit that code or to replace it with something new? Thank you. -- Andriy Gapon
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