Re: Finegrained a/c/mtime was Re: Directory notification pr
Jonathan Lundell (email@example.com)
Fri, 5 Oct 2001 06:41:39 -0700
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)
>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.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to firstname.lastname@example.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/