In message: <Pine.LNX.4.64.0701061811440.11581_at_hermes-1.csi.cam.ac.uk>
Tony Finch <dot_at_dotat.at> writes:
: On Sat, 6 Jan 2007, M. Warner Losh wrote:
: >
: > OSes usually deal with timestamps all the time for various things. To
: > find out how much CPU to bill a process, to more mondane things.
: > Having to do all these gymnastics is going to hurt performance.
:
: That's why leap second handling should be done in userland as part of the
: conversion from clock (scalar) time to civil (broken-down) time.
Right. And that's what makes things hard because the kernel time
clock needs to be monotonic, and leap seconds break that rule if one
does things in UTC such that the naive math just works (aka POSIX
time_t). Some systems punt on keeping posix time internally, but have
complications for getting leapseconds right for times they return to
userland....
Warner
Received on Sat Jan 06 2007 - 10:41:25 PST