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Date:      Fri, 26 Oct 2001 10:07:15 -0700 (PDT)
From:      Matthew Dillon <dillon@apollo.backplane.com>
To:        Julian Elischer <julian@elischer.org>
Cc:        Terry Lambert <tlambert2@mindspring.com>, Poul-Henning Kamp <phk@critter.freebsd.dk>, Peter Wemm <peter@wemm.org>, arch@FreeBSD.ORG
Subject:   Re: 64 bit times revisited..
Message-ID:  <200110261707.f9QH7F437553@apollo.backplane.com>
References:   <Pine.BSF.4.21.0110261046280.10928-100000@InterJet.elischer.org>

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    For UFS we obviously re-coopt the nanosecond field.  Thanks Kirk!
    I suggest simply changing di_atimensec (and friends) to di_atimemsb,
    to hold the msb 32 bits, allowing us to maintain backwards compatibility.

    The question before us is whether we should eat some of those 64 bits and
    attempt to store sub-second timestamps.

    This is a bad idea.  There's no point, because processors are only
    getting faster.  Even nanosecond resolution isn't enough and we have
    other issues simply due to new computing methodologies such as parallel
    and distributed processing.  'make's issues aren't enough to justify
    complexifying atime/ctime/mtime.

    The larger problem that we need to solve are the ridiculous calendar
    limitations.  We have to solve the problem *permanently* this time,
    we have to solve them obviously, with as little additional complexity
    as possible.  We have to have a solution that is *uniform* across the
    system, and a full 64 bit 1-second resolution field will do that. 
    We should not be screwing around with other clutter.

    I am not against adding additional fields to struct stat to support
    sub-second resolution for mtime, but I am against attempting to
    integrate such fields into st_atime/st_mtime/st_ctime directly.

    Unfortunately we only have two spare 64 bit fields in struct nstat.
    They aren't enough to fix the time fields and maintain backwards
    compatibility.  Unless I'm missing something here, we are going to have
    to roll new syscalls for *stat() and *utimes() (any others?)

						-Matt


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