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SubjectRe: Finegrained a/c/mtime was Re: Directory notification pr
At 3:27 PM -0700 2001-10-05, Petr Vandrovec wrote:
>On 5 Oct 01 at 14:15, Padraig Brady wrote:
>> >Another advantage of using the real time instead of a counter is that
>> >you can easily merge the both values into a single 64bit value and do
>> >arithmetic on it in user space. With a generation counter you would need
>> >to work with number pairs, which is much more complex.
>> >
>> ??
>> if (file->mtime != mtime || file->gen_count != gen_count)
>> file_changed=1;
>make needs comparing timestamps between two files. I cannot imagine
>how you can get this working (without network filesystem you can
>have global gen_count, but with network filesystem each server has
>its own gen_count... and using world-wide nanoseconds instead of world-wide
>gen_count looks much simpler to me ;-) )

Except for the world-wide-nanosecond-resolution synchronization problem....

Even keeping cycle-counter-based systems in sync within SMP systems
seems problematical, depending on how the counters are implemented.
/Jonathan Lundell.
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