Re: Make the git codebase thread-safe

On Wed, Feb 12, 2014 at 08:15:24PM +0100, David Kastrup wrote:

Stefan Zager [off-list ref] writes:

quoted

On Wed, Feb 12, 2014 at 10:50 AM, David Kastrup [off-list ref] wrote:

quoted

Really, give the above patch a try.  I am taking longer to finish it
than anticipated (with a lot due to procrastination but that is,
unfortunately, a large part of my workflow), and it's cutting into my
"paychecks" (voluntary donations which to a good degree depend on timely
and nontrivial progress reports for my freely available work on GNU
LilyPond).

I will give that a try.  How much of a performance improvement have
you clocked?

Depends on file type and size.  With large files with lots of small
changes, performance improvements get more impressive.

Some ugly real-world examples are the Emacs repository, src/xdisp.c
(performance improvement about a factor of 3), a large file in the style
of /usr/share/dict/words clocking in at a factor of about 5.

Again, that's with an SSD and ext4 filesystem on GNU/Linux, and there
are no improvements in system time (I/O) except for patch 4 of the
series which helps perhaps 20% or so.

So the benefits of the patch will come into play mostly for big, bad
files on Windows: other than that, the I/O time is likely to be the
dominant player anyway.

How much fragmentation does that add to the files, though?

Mike