Re: .LOW_RESOLUTION_TIME

[ali hagigat]

Dear Eli,

Time-stamp is checked before updating a file. In the last example you
mentioned, when a file is updated(this file is prerequisite of an
ultimate target), it shows that make has made its final decision to
update the ultimate target because it has started updating its
prerequisite!
So if the system removes sub-seconds of that prerequisite, make does
not think that the ultimate target is updated and it will update the
ultimate target finally!
So it does not mistakenly considers the ultimate target updated as the
manual is saying....


On Wed, Nov 10, 2010 at 3:08 PM, Eli Zaretskii <address@hidden> wrote:
>> Date: Wed, 10 Nov 2010 08:52:05 +0330
>> From: ali hagigat <address@hidden>
>>
>> Sorry but one sentence of the document does not make sense related to
>> Eli's example as it is saying:
>>
>> "The high resolution file time stamps of many modern file systems
>> lessen the chance of make incorrectly concluding that a file is up to
>> date."
>>
>> The time-stamp of 'src' is like 10:25:32.890 and 'dst' is 10:25:32.
>> So 'src' is newer than 'dst' and 'dst' needs to be updated and make
>> concludes that the file is out of date!!
>
> The manual is correct, but it has in mind a different situation, not
> the one after copying a file with a version of `cp' which loses
> sub-second time resolution.
>
> The situation the manual has in mind here is when a file is updated
> within several milliseconds or several tens of milliseconds.  (This is
> possible with today's powerful CPUs.)  If the filesystem only holds
> the times to the nearest second, the updated file will look to Make as
> if its time stamp didn't change, and the files for which this file is
> a prerequisite will look up to date, whereas they really aren't.
>