Message-Id: <200506102313.j5ANDe3d029629@delorie.com> Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com From: "Gary R. Van Sickle" To: Subject: RE: Making /bin/sh == bash. Has the time come? Date: Fri, 10 Jun 2005 18:13:31 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit In-Reply-To: <20050610150729.GA13181@trixie.casa.cgf.cx> X-IsSubscribed: yes Configuring wxWindows from cvs, on a 3.4GHz P4: Sh = Ash: real 3m55.351s user 5m8.610s sys 1m53.240s Sh = Bash: real 3m41.850s user 5m6.220s sys 1m53.426s Looks like the time has come. -- Gary R. Van Sickle > -----Original Message----- > From: cygwin-owner AT cygwin DOT com > [mailto:cygwin-owner AT cygwin DOT com] On Behalf Of Christopher Faylor > Sent: Friday, June 10, 2005 10:07 AM > To: cygwin AT cygwin DOT com > Subject: Making /bin/sh == bash. Has the time come? > > A long time ago, in a Cygwin release prior to B20.1, someone > made the decision to use "ash" as the standard /bin/sh for > Cygwin. The sole reason for doing this was that ash was > faster than bash. > > Later, at one point, I implemented a sorta-wannabe version of > vfork, and commissioned one of the people who worked for me > to modify ash to use vfork. This made ash even faster than > it was before. > > Recently, after too many hours hacking at vfork corner cases, > I came to the conclusion that getting vfork working correctly > was too difficult so, I turned off vfork in cygwin and asked > Corinna to modify ash to use /bin/sh again. > > So, that leaves us with an ash which is still faster. For example: > > e:\>time ash -c "i=0; while [ $i -lt 1000 ]; do i=$(expr $i > + 1); done" > 32.24user 9.72system 0:12.85elapsed 326%CPU > (0avgtext+0avgdata 11677696maxresident)k > 0inputs+0outputs (730699major+0minor)pagefaults 0swaps > > e:\>time bash -c "i=0; while [ $i -lt 1000 ]; do i=$(expr > $i + 1); done" > 49.86user 16.51system 0:23.04elapsed 288%CPU > (0avgtext+0avgdata 20525056maxresident)k > 0inputs+0outputs (1284873major+0minor)pagefaults 0swaps > > i.e., bash is twice as slow as ash. However: > > e:\>time bash -c "i=0; while [ $i -lt 1000 ]; do i=$(($i + > 1)); done" > 0.14user 0.01system 0:00.15elapsed 101%CPU > (0avgtext+0avgdata 15712maxresident)k > 0inputs+0outputs (982major+0minor)pagefaults 0swaps > > So, there are some constructs available in bash which, if you > assume that bash == /bin/sh, will result in much faster shell > script execution. > > And, anyone who reads this list regularly will know that we > get a lot of complaints about the differences between bash > and ash, which cause people to eventually copy bash to /bin/sh. > > So, in conversation with Corinna, I think that we're starting > to lean towards making /bin/sh == bash sometime soon. We > won't get rid of ash and will point to it when people send > the inevitable "Cygwin is slow!" > message here. > > I was thinking that we should have something like linux's > "alternatives" > command which would allow us to set up /bin/sh to whatever a > user decides is best for them, defaulting to /bin/bash. This > is, of course, trickier to do right on cygwin since you can't > use a cygwin symbolic link to do a 'ln -s /bin/bash /bin/sh' > but you could still do something with a copy, recording > preferences in a file. > > Anyway, I wanted to get people's feelings on making this > change. Is anyone actually relying on ash for some reason? > > cgf > > -- > Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple > Problem reports: http://cygwin.com/problems.html > Documentation: http://cygwin.com/docs.html > FAQ: http://cygwin.com/faq/ > -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/