Re: [PATCH 0/3] Un-pessimize "diff-index $commit -- $pathspec"

Linus Torvalds [off-list ref] writes:

On Mon, Aug 29, 2011 at 2:33 PM, Junio C Hamano [off-list ref] wrote:

quoted

Before and after applying this series, looking for changes in the kernel
repository with a fairly narrow pathspec gets a moderate speeds up.

"moderate speeds up"?

Looks like a big win to me. Admittedly it's already a pretty fast
operation, but script it and repeat it a million times, and that will
matter a lot more.

I guess the "--raw" diff part means that you are hiding the time to
make a real diff, which would otherwise swamp everything else. Even
so, this looks like a good improvement.

The topic started by Marat Radchenko in

    http://thread.gmane.org/gmane.comp.version-control.git/179926

who was trying to pick a single path (we do not know how deep it is), and
was comparing between these two:

  $ time git show branch:file | diff -u - file > /dev/null 
  real    0m0.003s
  user    0m0.000s
  sys     0m0.000s
  $ time git diff branch -- file > /dev/null 
  real    0m31.442s
  user    0m31.040s
  sys     0m0.380s

Replacing "diff -u" with "git diff --no-index" in the former didn't make
much of a difference. It turned out that Marat had 603k paths in the index
and the most of the time was spent in the unpack machinery.

On Mon, Aug 29, 2011 at 3:05 PM, Junio C Hamano [off-list ref] wrote:

The topic started by Marat Radchenko in

Ugh, that's ugly. Is it verified to solve Marat's nasty case too?

But yeah, ack on the series.

                 Linus