TALPA strides forward [LWN.net]

TALPA strides forward

Posted Aug 28, 2008 9:16 UTC (Thu) by liljencrantz (guest, #28458)
In reply to: TALPA strides forward by evgeny
Parent article: TALPA strides forward

Sure, many other build systems, like scons, allow you to use file checksums instead of mtime, for determining if a file has been modified. But once your project gets big enough, that is slow. The largest project I've used scons contained a few megabytes of source code, and scons would take a noticable amount of time checking the dependencies. So it's not only make.

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TALPA strides forward

Posted Aug 28, 2008 10:30 UTC (Thu) by rvfh (guest, #31018) [Link] (1 responses)

Looking at mtime should be enough, provided that we look for any change in it and not just for it to be greater that than of another file.

Let me explain: the time maybe wrong a one machine causing the mtime go backwards, like when editing a file that's on a build server share, but it is very unlikely that the mtime will be exactly the same as it was before edition.

It is quicker to check mtime for a change than checksuming the whole file.

TALPA strides forward

Posted Sep 4, 2008 20:27 UTC (Thu) by renox (guest, #23785) [Link]

Mmm, in this case a version number attribute associated with each file would be better (if only because SW developers would be less likely to compare mtime of different files), though it may be a bit costly to maintain especially on CPU with don't have an atomic increase instruction..