My problem is that the kernel is not currently capable of supplying what Erik defines, to the process level even internally, and even for his described applications (delays of a small interval, tiny retransmission times), it's not clear that the traditional sleep, which has *always* been sloppy, is anyway the right model; and certainly not for any more general application. I had a quick read through some papers and theses last night, and it certainly isn't clear cut.
What values could the kernel currently supply to a query interface? There are no particular bounds on anything, which was rather my point. I had a similar problem *inside the kernel* when dealing with a fast network interface on the Blue Gene. The whole thing started with an "historical question": "why is sleep(2) limited to resolution HZ in the portable code? ..." and I gave what I think is the correct reply historically: "the relative unimportance of sleep?", but as usual that didn't go down very well. For relatively small delays, sleep -> tsleep isn't right. Most of the ways of making "high-precision" timers available at user level contain a lot of overhead, or frustration when trying to use them (eg, POSIX sends a signal, never a harbinger of speed or ease of use). I've probably just had my fill of general-purpose systems that confuse "not too often slow" with "timely". It's less of a problem for Plan 9, than Nix, where I'd like to see any new things added be sound. On 29 November 2012 08:12, <arn...@skeeve.com> wrote: > Erik's problem boils down to "the kernel knows what it can do and is > quite capable but i can't get it at from user space".
