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Date: Sat, 27 Jul 2002 11:05:14 -0400 (EDT)
From: David E Euresti <davie AT MIT DOT EDU>
To: <cygwin AT cygwin DOT com>
Subject: RE: Does cygwin slow things down?
In-Reply-To: <000201c234fc$7b265d70$70124142@montage>
Message-ID: <Pine.GSO.4.30L.0207271101180.24762-100000@magic-pi-ball.mit.edu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

Actually I believe I have found my bottleneck, select.

Each select call in win32 takes 13usecs, while a select call in Cygwin
takes 970usecs.  Now I know that there's some extra magic inside select to
make it work with pipes and files and stuff, but I just thought I'd
mention that that was the problem I'm having.  What I plan to do is before
calling select check to see if they are all sockets, if they are I'll just
extract the handles and call win32 select, I'll see what happens when I
do that.

On Fri, 26 Jul 2002, Dennis McCunney wrote:

> > -----Original Message-----
> > From: cygwin-owner AT cygwin DOT com
> > [mailto:cygwin-owner AT cygwin DOT com]On Behalf
> > Of David E Euresti
> > Sent: Friday, July 26, 2002 9:57 AM
> > To: cygwin AT cygwin DOT com
> > Subject: Does cygwin slow things down?
> >
> > Has anybody done any tests to see just how fast cygwin is?
> > Like how do networking applications behave and the like?
> > I just ported a pretty large project and I've been noticing
> > that it's much
> > slower, and I was wondering if it was cygwin that did it.
> > So anybody compiled something like apache who can tell me if
> > it runs much
> > slower?
>
> Do a search of the mailing list archives.  This topic has gotten a _lot_ of
> discussion.
>
> Bottom line: Cygwin _is_ slower than a native Unix/Linux app, sometimes by
> an order of magnitude.  This is expected and unavoidable.  After all, Cygwin
> is an emulator, inserting a POSIX compatibility layer between apps compiled
> using it and the underlying Win32 OS.  Some POSIX calls simply don't have a
> clean mapping to Win32 calls, and there will always be overhead in
> emulation.
>
> If you profile your code, you can probably tell where the slowdown is
> occuring.  You may be able to change your code to run faster.  You may also
> identify areas where Cygwin could do things better. Patches are always
> gratefully accepted.
>
> > Thanks,
> > David
> ______
> Dennis
>
>


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