René Scharfe wrote:
Am 29.03.2010 03:42, schrieb SungHyun Nam:
Hello,
If I run a attached script for bunzipped attached files, I get:
(To reduce size, I removed many lines and bzipped.)
$ ./mk.sh
time diff -u x3 x4>/dev/null 2>&1
real 0m0.011s
user 0m0.000s
sys 0m0.010s
time git diff>/dev/null 2>&1
real 0m0.193s
user 0m0.190s
sys 0m0.000s
$ git version
git version 1.7.0.2.273.gc2413
$ diff --version
diff (GNU diffutils) 2.8.1
...
Well, though the files are ascii file, they includes a random
hexa-decimal datas, so that I don't interest the diff result at
all. But the real problem is 'rebasing took so long if the file
was changed'. Because the git tree includes several such a file,
if they changed, rebase took some miniutes for every branch.
Such a branch includes a few lines of changes for a C source file,
though. Now I'm waiting an hour to finish rebasing all the
branches and yet a rebasing script is running... :-(
I can reproduce it; I concatenated your example files five times to get
meaningful timings (x1 = five times x3, x2 = five times x4).
The difference between GNU diff and git diff is that the latter is trying
hard to minimize the size of the diff. Each user of the xdiff library in
git turns on the XDF_NEED_MINIMAL flag, which makes it very expensive
(specifically the function xdl_split()).
The following patch is not meant for inclusion, but rather to start a
dicussion. Is XDF_NEED_MINIMAL a good default to have?
The patch removes XDF_NEED_MINIMAL and replaces it with XDF_QUICK, with
reversed meaning. XDF_QUICK is only set if the new option --quick is
given, so without it the old behaviour is retained. Some numbers:
The patch is great for me. Thanks!
Added 'time git diff --quick' to the mk.sh and ran with a
original file (about 180000 lines):
$ ./mk.sh
time diff -u x3 x4 >/dev/null 2>&1
real 0m0.794s
user 0m0.720s
sys 0m0.010s
time git diff >/dev/null 2>&1
real 0m44.687s
user 0m44.670s
sys 0m0.020s
time git diff --quick >/dev/null 2>&1
real 0m1.853s
user 0m1.840s
sys 0m0.010s
Thanks!
namsh
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