This is the mail archive of the cygwin mailing list for the Cygwin project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

RE: Making /bin/sh == bash. Has the time come?


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@cygwin.com 
> [mailto:cygwin-owner@cygwin.com] On Behalf Of Christopher Faylor
> Sent: Friday, June 10, 2005 10:07 AM
> To: cygwin@cygwin.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/


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]