xstat: Add a pair of system calls to make extended file stats available [ver #6]
in [Kernel]
|
Prev: net-next: fix LRO feature update in vmxnet3
Next: touchscreen/nuc900: fix wrong setup_timer parameter
From: Mark Harris on 16 Jul 2010 02:30 > struct xstat_time { > unsigned long long tv_sec, tv_nsec; > }; unsigned? Existing filesystems support on-disk timestamps representing times prior to the epoch. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Mark Harris on 17 Jul 2010 02:00
David Howells wrote: > With a 2:2 split between exponent > (tv_gran_units) and mantissa (tv_granularity), you can do: > > UNIT SECONDS/UNIT EXPONENT MANTISSA > nanoseconds 0.000000001 -9 1 > microseconds 0.000001 -6 1 > millseconds 0.001 -3 1 > seconds 1 0 1 > minutes 60 1 6 > hours 3600 2 36 > days 86400 2 864 > weeks 604800 2 6048 At least for the in-tree filesystems, I do not see any that keep timestamps with a granularity larger than 2s. For that, a simple 32-bit tv_granularity in nanoseconds (not limited to 1e9) would suffice, and there is no need for the complexity of dealing with a separate exponent. If there is a need to handle larger granularity, its msb could potentially be used to indicate that the number is in seconds instead of nanoseconds. This is convenient because the timestamp is already broken down into sec and nsec fields. So this bit would then indicate that the granularity applies to the tv_sec field, and that tv_nsec is not in use. But even this is overkill if no one uses a granularity larger than 2s. - Mark -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |