Re: Make the git codebase thread-safe

[Mike Hommey <mh@glandium.org>]

On Wed, Feb 12, 2014 at 08:15:24PM +0100, David Kastrup wrote:
> Stefan Zager <szager@chromium.org> writes:
> 
> > On Wed, Feb 12, 2014 at 10:50 AM, David Kastrup <dak@gnu.org> wrote:
> >
> >> 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