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Date: Wed, 12 Nov 2014 11:24:25 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Notable performance improvement in 64-bit build
Message-ID: <20141112102425.GY2782@calimero.vinschen.de>
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On Nov 12 00:52, Ivan Todoroski wrote:
> Hello everyone,
>=20
> I'm just curious, has there been any special focus on performance
> improvements in the 64-bit version compared to 32-bit?
>=20
> I'm asking because I recently upgraded from 32-bit to 64-bit Cygwin, and I
> noticed that my bash prompt would show up noticeably quicker when I opene=
d a
> new Cygwin shell (I have a rather complicated ~/.profile script, so the
> delay is actually visible to the eye).
>=20
> At first I thought it was just some sort of placebo effect and I was
> imagining it, but the effect seemed so persistent that I just had to perf=
orm
> some measurements.
>=20
> What I found was that under 32-bit Cygwin my ~/.profile script is executed
> in 507ms (average of 30 runs), but under 64-bit Cygwin the exact same scr=
ipt
> gets executed in 376ms (again, 30-run average). Both measurements were do=
ne
> on the same machine with 32-bit and 64-bit Cygwin installed side by side
> (both freshly updated to their latest respective versions).
>=20
> That's a whopping 33% performance improvement!
>=20
> So I was just curious if anyone had any speculations on what exactly might
> have caused this performance increase. :)

Uhm... actually we don't know exactly either.  It is said that the WOW64
emulation may introduce a 5% penalty, but that doesn't explain 33%.  I
made some tests on my own and I had performance differences of a meager
1% and up to 83% in various different `make' scenarios, so I guess it's
not quite a safe bet to say 64 bit Cygwin is faster.  But all in all
we're rather happy with the result.

You may be interested to update to the test release 1.7.33, see
https://cygwin.com/ml/cygwin-announce/2014-11/msg00013.html

It introduces two changes, one in terms of user and group account
handling which should speed up process startup noticably, the other a
change in exception handling which should speed up the 64 bit version by
removing some code overhead per system call.

> In any case, kudos to the Cygwin developers, great job on the 64-bit buil=
d!

Thanks a lot!


Corinna

--=20
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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