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TALPA strides forward

TALPA strides forward

Posted Aug 29, 2008 16:45 UTC (Fri) by bfields (subscriber, #19510)
In reply to: TALPA strides forward by njs
Parent article: TALPA strides forward

In practice I'm pretty sure that the mtime *would* always be updated, though, because in linux, in-memory inodes always get nanosecond-accurate timestamps.

That's not true. On a recent kernel try running a simple test program, that does e.g., write, stat, usleep(x), write, stat. You'll see that on ext2/ext3 "x" has to be at least a million (a second) before you see a difference in the two stats, and that on something like xfs, it has to be at least a thousand to ten thousand (a few milliseconds--the time resolution used is actually jiffies).

(On older kernels I think the ext2/3 behavior might look like xfs's; that was fixed because of problems with unexpected changes in timestamps (due to lost nanoseconds field) when an inode got flushed out of cache and then read back.)


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TALPA strides forward

Posted Aug 30, 2008 1:47 UTC (Sat) by njs (guest, #40338) [Link]

I was aware of the issues with confusing timestamp changes, but didn't realize it had been changed. Thanks.


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