[ntp:hackers] ntp and signalled IO
phk at phk.freebsd.dk
Tue Apr 18 17:30:16 UTC 2006
In message <2886.1145380712 at sa.vix.com>, Paul Vixie writes:
>> >that's currently all in how one sets up the callbacks. priority queuing is
>> >considered an upper level matter. but i'm willing to add something like
>> >"evPriorityFD(evContext, evFileID, int)" if that's of any use here.
>> I'm simply talking about something as trivial as which file descriptor
>> has the lower integer numer so it gets taken first by select()
>evGetNext currently implements descriptor magnitude fairness, in that it
>will remember what descriptor it left off at in the previous fd_mask scan,
>and start there again next time. are you asking for a global option to
>turn this off and always call select() (never reusing masks between calls
>to evGetNext) and always start from zero?
Well, it's more like whenever select has been called, always handle
any events on this one "hot" filedescriptor first.
But I would propose we table the issue for now.
Most if not all modern systems have other means of timestamping,
and those that do not are unlikely to have high-performance
So I would want to focus on getting things working on the modern
OS's and then see how bad things look on the old ones before I
say we should go and do a lot about this particular nit.
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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