Re: use lutimens

[Jim Meyering]

Eric Blake wrote:
> According to Jim Meyering on 10/10/2009 1:35 PM:
>> Those look fine.  Thanks!
>> I compared the performance of your modified touch
>> on a tmpfs file system on a system running rawhide,
>> creating 100,000 empty files (names 1..100,000), and found
>> no significant difference when running touch with no options.
>
> Try it again with 'touch -a' or 'touch -m'.  The savings come when
> changing only one of the two timestamps: previously, touch had to stat()
> to learn the time to preserve, as well as gettime() to learn what time to
> change; but the new code can rely on the kernel to do both of those actions.

Same result.  There is no significant difference on GNU/Linux.

I do confirm (via strace) that the fstat syscall is gone,
but figure we've merely moved the burden into futimens.