Re: MinGW port usable

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Jan 30, 2007, 14:35 UTC
Message-ID: <Pine.LNX.4.63.0701301524360.22628@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To: <Pine.LNX.4.64.0701291438580.3611@woody.linux-foundation.org>

Hi,

On Mon, 29 Jan 2007, Linus Torvalds wrote:

> Can you elaborate about any performance differences, especially with 
> cygwin? Does this make git perform reasonably on Windows, or are the 
> performance problems as bad as with cygwin?

On the git repository, using MinGW:

	$ time git-rev-list next > /dev/null

	real    0m0.320s
	user    0m0.031s
	sys     0m0.000s

	$ time git-rev-list next > /dev/null

	real    0m0.320s
	user    0m0.015s
	sys     0m0.015s

	$ time git-rev-list next > /dev/null

	real    0m0.352s
	user    0m0.015s
	sys     0m0.000s

Using cygwin:

	$ time git-rev-list next > /dev/null

	real    0m0.750s
	user    0m0.421s
	sys     0m0.140s

	$ time git-rev-list next > /dev/null

	real    0m0.750s
	user    0m0.374s
	sys     0m0.233s

	$ time git-rev-list next > /dev/null

	real    0m0.750s
	user    0m0.374s
	sys     0m0.218s

IOW MinGW wins hands down with an average 0.33s vs cygwin with an average 0.75s. (I am fairly certain that you must not trust sys times.)

I have no idea why, as the big show-stopper fork() is not even involved.

Now, for something different: git-log. On MinGW:

	$ time git-log next > /dev/null

	real    0m1.594s
	user    0m0.015s
	sys     0m0.015s

	$ time git-log next > /dev/null

	real    0m1.562s
	user    0m0.031s
	sys     0m0.000s

	$ time git-log next > /dev/null

	real    0m1.610s
	user    0m0.015s
	sys     0m0.015s

On Cygwin:

	$ time git-log next > /dev/null

	real    0m2.063s
	user    0m0.827s
	sys     0m1.031s

	$ time git-log next > /dev/null

	real    0m2.085s
	user    0m0.780s
	sys     0m1.061s

	$ time git-log next > /dev/null

	real    0m2.047s
	user    0m0.686s
	sys     0m1.171s

That's a bit less obvious: 1.589s for MinGW vs. 2.065s for Cygwin.

These are all hot-cache numbers, since the cold-cache performance of Windows is not easily triggered. (FWIW the first git-log on Cygwin -- which was cold-cache -- took over 10 seconds.)

Ciao, Dscho