On Friday 2007 March 02 16:21, Karl Hasselström wrote: > However, given that your file timestamps have been bumped (without > file content changes), it's a performance bug in your make tool if Actually, git is as good as it could reasonably get in this regard. Let's say you did this: git checkout branch1 git checkout branch2 git checkout branch1 Git will only touch the timestamps of files that are different between the branches. If the same file is in both branches, then that one remains untouched in your working tree (it's tricks like this that make git so blindingly fast). The fact that you've changed back from branch2 to branch1 is the bone of contention - how is git meant to know that you haven't done a compilation while you were on branch2 and hence changed the files that untracked files depend on? The /only/ sane thing it can do is, in both cases, update changed files to have the current time. Perhaps an example would make it clearer: git checkout branch1 # sourcefile.c changes, so git touches the timestamp # make would rebuild sourcefile.o git checkout branch2 # sourcefile.c changes, so git touches the timestamp # make would rebuild sourcefile.o git checkout branch1 # sourcefile.c changes, so git touches the timestamp # make would rebuild sourcefile.o That's all exactly right, make knows in each case the the ".o" file is out of date because it has a timestamp earlier than sourcefile.c Now take the suggestion that timestamps from the repository version should be restored and do the same thing: git checkout branch1 # sourcefile.c changes, git sets the timestamp to $timestamp1 # make would rebuild sourcefile.o (setting its timestamp to $now) git checkout branch2 # sourcefile.c changes, so sets the timestamp to $timestamp2 # make wouldn't rebuild sourcefile.o because $timestamp2 < $now git checkout branch1 # sourcefile.c changes, so git sets the timestamp to $timestamp1 # make wouldn't rebuild sourcefile.o because $timestamp1 < $now All very wrong; in two out of the three builds, the wrong sourcefile.o ends up in the final object. What git does now is absolutely the right thing. It keeps unnecessary rebuilds to the safest minimum. Andy -- Dr Andy Parkins, M Eng (hons), MIET andyparkins@xxxxxxxxx - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html