[racket] Efficiency of tight loops in Racket

The following shows 100% cpu usage on both processors of my dual core
machine running with Windows 7.
I don't know why my earlier attemps, some time ago, did not work.
I now see that the docs tell that futures are supported for Windows too.
Thanks, Jos.

DrRacket, version 5.0.99.6--2011-01-18(c12d52f/a) [3m].

#lang racket
(require racket/future)
(processor-count) ; -> 2
(define f (future (lambda () (let loop () (loop)))))
(let loop () (loop))
; (touch f) 

> -----Original Message-----
> From: users-bounces at racket-lang.org 
> [mailto:users-bounces at racket-lang.org] On Behalf Of Jos Koot
> Sent: 18 January 2011 09:31
> To: 'Robby Findler'
> Cc: users at racket-lang.org
> Subject: Re: [racket] Efficiency of tight loops in Racket
> 
> I have seen these pages before. There are many caveats and I 
> probably went into them. I'll try to do the mandelbrot 
> example in its various versions and compare their timings, 
> while observing CPU usage.
> Jos
> 
> > -----Original Message-----
> > From: robby.findler at gmail.com
> > [mailto:robby.findler at gmail.com] On Behalf Of Robby Findler
> > Sent: 17 January 2011 21:56
> > To: Jos Koot
> > Cc: Noel Welsh; users at racket-lang.org
> > Subject: Re: [racket] Efficiency of tight loops in Racket
> > 
> > If you have not seen this yet, this is where you want to start:
> > 
> > http://docs.racket-lang.org/guide/performance.html#%28part._ef
> fective-futures%29
> > 
> > Robby
> > 
> > On Mon, Jan 17, 2011 at 2:40 PM, Jos Koot <jos.koot at telefonica.net> 
> > wrote:
> > > I trieed some examples of my own. But I shall try the
> > examples of the
> > > docs ASAP.
> > > More tomorrow, for now it's my bedtime.
> > > Jos
> > >
> > >
> > >
> > >
> > >> -----Original Message-----
> > >> From: robby.findler at gmail.com
> > >> [mailto:robby.findler at gmail.com] On Behalf Of Robby Findler
> > >> Sent: 17 January 2011 20:43
> > >> To: Jos Koot
> > >> Cc: Noel Welsh; users at racket-lang.org
> > >> Subject: Re: [racket] Efficiency of tight loops in Racket
> > >>
> > >> With futures you have to be careful; it is easy to write 
> code that 
> > >> doesn't end up actually being parallel. Did you try the
> > examples from
> > >> the docs?
> > >>
> > >> Robby
> > >>
> > >> On Mon, Jan 17, 2011 at 1:27 PM, Jos Koot
> > <jos.koot at telefonica.net>
> > >> wrote:
> > >> > I did try futures, but did not observe two processors 
> being used 
> > >> > simultaneously.
> > >> > Jos
> > >> >
> > >> >> -----Original Message-----
> > >> >> From: robby.findler at gmail.com
> > >> >> [mailto:robby.findler at gmail.com] On Behalf Of Robby Findler
> > >> >> Sent: 17 January 2011 20:22
> > >> >> To: Jos Koot
> > >> >> Cc: Noel Welsh; users at racket-lang.org
> > >> >> Subject: Re: [racket] Efficiency of tight loops in Racket
> > >> >>
> > >> >> Oh, yes. DrRacket does not try to use two processors
> > for anything
> > >> >> (unless your program uses futures or places, of course).
> > >> >>
> > >> >> Robby
> > >> >>
> > >> >> On Mon, Jan 17, 2011 at 10:25 AM, Jos Koot
> > >> <jos.koot at telefonica.net>
> > >> >> wrote:
> > >> >> > Thanks for your reply.
> > >> >> > What I am observing is that when running DrScheme
> > >> without any other
> > >> >> > apps running, only one processor is used at a time,
> > >> >> although control
> > >> >> > often swichtes bnetween the two processors. I also
> > observe that
> > >> >> > windows 7 aborts DrScheme when more than 2Gbyte of
> > >> memory is being
> > >> >> > used. I have set the memory limit of DrScheme to
> > infite and for
> > >> >> > windows to about 5 Gbyte. Under windows xp virtual memory
> > >> >> did function
> > >> >> > well, but that was with 1 Gbyte of memory and
> > trashing made it
> > >> >> > impossible to go up to 2 Gbyte. Now I have two cores of 2
> > >> >> Gbyte, but can't put my machine to thrash on page swapping.
> > >> >> > Jos
> > >> >> >
> > >> >> >> -----Original Message-----
> > >> >> >> From: robby.findler at gmail.com 
> > >> >> >> [mailto:robby.findler at gmail.com] On Behalf Of Robby Findler
> > >> >> >> Sent: 17 January 2011 16:14
> > >> >> >> To: Noel Welsh
> > >> >> >> Cc: Jos Koot; users at racket-lang.org
> > >> >> >> Subject: Re: [racket] Efficiency of tight loops in Racket
> > >> >> >>
> > >> >> >> I think the real reason is actually much sadder: no one on
> > >> >> the core
> > >> >> >> team regularly uses windows. Well, until about a month
> > >> ago, when I
> > >> >> >> started using windows for my development tasks so
> > >> >> hopefully that'll
> > >> >> >> change.
> > >> >> >>
> > >> >> >> But I'm not sure what Jos is observing and I was
> > >> expecting a reply
> > >> >> >> from Kevin or Matthew on this -- places are still pretty 
> > >> >> >> experimental.
> > >> >> >>
> > >> >> >> Robby
> > >> >> >>
> > >> >> >> On Mon, Jan 17, 2011 at 8:58 AM, Noel Welsh
> > >> <noelwelsh at gmail.com>
> > >> >> >> wrote:
> > >> >> >> > I've seen lots of recent commits dealing w/ Windows 7
> > >> / 64-bit
> > >> >> >> > support, so I expect it is simply time. Windows is not
> > >> >> as developer
> > >> >> >> > friendly as Unix so likely to receive new 
> features last (as
> > >> >> >> a guess).
> > >> >> >> >
> > >> >> >> > N.
> > >> >> >> >
> > >> >> >> > On Sat, Jan 15, 2011 at 5:22 PM, Jos Koot
> > >> >> >> <jos.koot at telefonica.net> wrote:
> > >> >> >> >> Is there a specific reason why there is no parallel
> > >> >> >> support for place
> > >> >> >> >> on a dual core processor with Windows 7.
> > >> >> >> >> Thanks, Jos
> > >> >> >> > _________________________________________________
> > >> >> >> >  For list-related administrative tasks:
> > >> >> >> >  http://lists.racket-lang.org/listinfo/users
> > >> >> >> >
> > >> >> >
> > >> >> >
> > >> >
> > >> >
> > >
> > >
> 
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