From: Alex Riesen <raa.lkml@gmail.com>
Date: Fri, 08 May 2009 08:17:03 GMT
Subject: Re:
Message-ID: <81b0412b0905080117v3aad0c44o7b3bbcc7fe70d3b1@mail.gmail.com>
In-Reply-To: <alpine.LFD.2.01.0905071446500.4983@localhost.localdomain>

2009/5/7 Linus Torvalds <torvalds@linux-foundation.org>:
>
> Somebody should check. It would be interesting to hear about whether this
> makes a performance impact, especially with slow filesystems and/or other
> operating systems that have a relatively higher cost for 'lstat()'.
>

I did (cygwin). My guess, the improvement is completely dwarfed by the
other overheads (like starting git and writing files).

# Without the patch
real    11m22.338s
user    0m54.629s
sys     8m33.638s

# With checkout index preload
real    11m14.361s
user    0m46.609s
sys     7m56.300s

The script:

#!/bin/sh

if [ "$1" = setup ]; then
    for i in 1 2 3 4
    do
        n=$(date)
        for f in `seq 1 10000`
        do
            echo "$n" >file$f
        done
        git add .
        printf "Commit $i:"
        git commit -m"$n"
    done
    exit
fi

export GIT_EXEC_PATH=/d/git-win
time for f in `seq 1 10`
do
    $GIT_EXEC_PATH/git checkout master~3 &&
    $GIT_EXEC_PATH/git checkout master~2 &&
    $GIT_EXEC_PATH/git checkout master~1 &&
    $GIT_EXEC_PATH/git checkout master
done
exit