Re: What's the difference between `git show branch:file | diff -u - file` vs `git diff branch file`?

Junio C Hamano [off-list ref] writes:

Junio C Hamano [off-list ref] writes:

quoted

Of course the merge machinery does not know anything about pruning with
pathspec, so it is understandable (not justifiable) it would walk the full
tree.

Will try to find time this week to cook up something.

This is still rough, but seems to pass the test suite, and gives me some
performance boost when applied to the kernel tree:

    (without patch)
    $ time git diff --raw --cached v2.6.30 -- virt/kvm
    real    0m0.114s
    user    0m0.088s
    sys     0m0.028s

    (with patch)
    $ time ./git diff --raw --cached v2.6.30 -- virt/kvm
    real    0m0.075s
    user    0m0.068s
    sys     0m0.008s

Heh, this is even better without --cached.

    (without patch)
    $ /usr/bin/time git diff --raw v2.6.27 -- net/ipv6
    real    0m0.538s
    user    0m0.492s
    sys     0m0.048s

    (with patch)
    $ /usr/bin/time git diff --raw v2.6.27 -- net/ipv6
    real    0m0.038s
    user    0m0.028s
    sys     0m0.012s