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 ;-) )
Best regards,
Petr Vandrovec
[email protected]
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.