[webkit-dev] Tip: Use 64-bit git binaries on Mac OS X

Mihai Parparita mihaip at chromium.org
Tue Dec 7 17:03:11 PST 2010

Thanks for the reminder about NO_MMAP. I just tried it out, and things
appeared to be slower with it, so it doesn't seem to be a good idea.

I'll contact the maintainer about providing fat 32/64-bit binaries by
default. The resulting .dmg is 8.5MB (vs. 4.5MB for the i386-only
one), so I think the bloat concerns are minimal.


On Tue, Dec 7, 2010 at 4:26 PM, Evan Martin <evan at chromium.org> wrote:
> It seems from the bug Mihai linked to that the Git+OS X maintainer
> thought the only benefit of a 64-bit binary was being able to handle
> larger files, but in fact the real benefit is that the increased
> address space of a 64-bit binary lets you mmap larger regions.  So it
> seems reasonable you could convince the maintainer.
> But really, large mmap regions is mostly working around the fact that
> Mihai was experiencing mmap taking 40ms.  Git Master Shawn Pearce said
> to me: "Try compiling Git with make NO_MMAP=1 and tell me how you like
> it. Git comes with a "replacement" mmap() implementation that does
> malloc()+read(). This was primarily meant for Win32 cases, but might
> be useful on Mac OS X."  In the old thread on the Git list about OS X
> performance that Mihai linked to in his blog post, Linus Torvalds
> seemed to indicate that he only expected mmap to have performance
> comparable to read on Linux, not on other platforms.
> So I'd maybe suggest trying that as well and then telling the Git+OS X
> maintainer which combination of settings is the best.  :)
> On Tue, Dec 7, 2010 at 4:14 PM, Eric Seidel <eric at webkit.org> wrote:
>> Can we evangelize the code.google.com project?
>> On Dec 7, 2010 4:04 PM, "Mihai Parparita" <mihaip at chromium.org> wrote:
>>> After complaining to a Linux-using friend for the n-th time that "git
>>> status" was much slower on my Snow Leopard machine than on his Linux
>>> box, I decided to look into why this is. As it turns out, most people
>>> get git binaries from http://code.google.com/p/git-osx-installer/,
>>> which are 32-bit. Switching to 64-bit binaries made git status go from
>>> 6.58s to 2.50s (mainly because this does fewer mmaps).
>>> You can download a 64-bit binary installer from
>>> https://github.com/downloads/mihaip/git_osx_installer/git-,
>>> or you can build it yourself (more details at
>>> http://blog.persistent.info/2010/12/making-git-faster-on-large-repositories.html).
>>> Mihai
>>> _______________________________________________
>>> webkit-dev mailing list
>>> webkit-dev at lists.webkit.org
>>> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
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