Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-11 Thread Francesc Alted
A Thursday 11 March 2010 14:35:49 Gael Varoquaux escrigué: > > So, in my experience, numpy.memmap is really using that large chunk of > > memory (unless my testbed is badly programmed, in which case I'd be > > grateful if you can point out what's wrong). > > OK, so what you are saying is that my a

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-11 Thread Gael Varoquaux
On Thu, Mar 11, 2010 at 02:26:49PM +0100, Francesc Alted wrote: > > I believe that your above assertion is 'half' right. First I think that > > it is not SWAP that the memapped file uses, but the original disk space, > > thus you avoid running out of SWAP. Second, if you open several times the > >

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-11 Thread Francesc Alted
A Thursday 11 March 2010 10:36:42 Gael Varoquaux escrigué: > On Thu, Mar 11, 2010 at 10:04:36AM +0100, Francesc Alted wrote: > > As far as I know, memmap files (or better, the underlying OS) *use* all > > available RAM for loading data until RAM is exhausted and then start to > > use SWAP, so the "

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-11 Thread Nadav Horesh
Nadav -Original Message- From: numpy-discussion-boun...@scipy.org on behalf of Gael Varoquaux Sent: Thu 11-Mar-10 11:36 To: Discussion of Numerical Python Subject: Re: [Numpy-discussion] multiprocessing shared arrays and numpy On Thu, Mar 11, 2010 at 10:04:36AM +0100, Francesc A

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-11 Thread Gael Varoquaux
On Thu, Mar 11, 2010 at 10:04:36AM +0100, Francesc Alted wrote: > As far as I know, memmap files (or better, the underlying OS) *use* all > available RAM for loading data until RAM is exhausted and then start to use > SWAP, so the "memory pressure" is still there. But I may be wrong... I believ

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-11 Thread Francesc Alted
A Sunday 07 March 2010 20:03:21 Gael Varoquaux escrigué: > On Sun, Mar 07, 2010 at 07:00:03PM +, René Dudfield wrote: > > 1. Mmap'd files are useful since you can reuse disk cache as program > > memory. So large files don't waste ram on the disk cache. > > I second that. mmaping has worked ve

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-07 Thread Gael Varoquaux
On Sun, Mar 07, 2010 at 07:00:03PM +, René Dudfield wrote: > 1. Mmap'd files are useful since you can reuse disk cache as program > memory. So large files don't waste ram on the disk cache. I second that. mmaping has worked very well for me for large datasets, especialy in the context of re

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-07 Thread René Dudfield
On Fri, Mar 5, 2010 at 7:29 PM, Brian Granger wrote: > Francesc, > >> Yeah, 10% of improvement by using multi-cores is an expected figure for >> memory >> bound problems.  This is something people must know: if their computations >> are >> memory bound (and this is much more common that one may in

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-06 Thread Nadav Horesh
the memory mapped file from the child process. Nadav -Original Message- From: numpy-discussion-boun...@scipy.org on behalf of Brian Granger Sent: Fri 05-Mar-10 21:29 To: Discussion of Numerical Python Subject: Re: [Numpy-discussion] multiprocessing shared arrays and numpy Francesc, Yeah

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-05 Thread Brian Granger
> > -Original Message- > > From: numpy-discussion-boun...@scipy.org on behalf of Francesc Alted > > Sent: Thu 04-Mar-10 15:12 > > To: Discussion of Numerical Python > > Subject: Re: [Numpy-discussion] multiprocessing shared arrays and numpy > > > > What kind o

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-05 Thread Francesc Alted
A Friday 05 March 2010 14:46:00 Gael Varoquaux escrigué: > On Fri, Mar 05, 2010 at 08:14:51AM -0500, Francesc Alted wrote: > > > FWIW, I observe very good speedups on my problems (pretty much linear > > > in the number of CPUs), and I have data parallel problems on fairly > > > large data (~100Mo a

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-05 Thread Gael Varoquaux
On Fri, Mar 05, 2010 at 08:14:51AM -0500, Francesc Alted wrote: > > FWIW, I observe very good speedups on my problems (pretty much linear in > > the number of CPUs), and I have data parallel problems on fairly large > > data (~100Mo a piece, doesn't fit in cache), with no synchronisation at > > all

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-05 Thread Francesc Alted
Gael, On Fri, Mar 05, 2010 at 10:51:12AM +0100, Gael Varoquaux wrote: > On Fri, Mar 05, 2010 at 09:53:02AM +0100, Francesc Alted wrote: > > Yeah, 10% of improvement by using multi-cores is an expected figure for > > memory bound problems. This is something people must know: if their > > computati

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-05 Thread Gael Varoquaux
On Fri, Mar 05, 2010 at 09:53:02AM +0100, Francesc Alted wrote: > Yeah, 10% of improvement by using multi-cores is an expected figure for > memory bound problems. This is something people must know: if their > computations are memory bound (and this is much more common that one > may initially thi

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-05 Thread Francesc Alted
t; > Nadav. > > > -Original Message- > From: numpy-discussion-boun...@scipy.org on behalf of Francesc Alted > Sent: Thu 04-Mar-10 15:12 > To: Discussion of Numerical Python > Subject: Re: [Numpy-discussion] multiprocessing shared arrays and numpy > > What ki

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-04 Thread Nadav Horesh
: [Numpy-discussion] multiprocessing shared arrays and numpy What kind of calculations are you doing with this module? Can you please send some examples and the speed-ups you are getting? Thanks, Francesc A Thursday 04 March 2010 14:06:34 Nadav Horesh escrigué: > Extended module that I u

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-04 Thread Francesc Alted
oresh > Sent: Thu 04-Mar-10 11:55 > To: Discussion of Numerical Python > Subject: RE: [Numpy-discussion] multiprocessing shared arrays and numpy > > Maybe the attached file can help. Adpted and tested on amd64 linux > > Nadav > > > -Original Message- > From: n

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-04 Thread Nadav Horesh
-boun...@scipy.org on behalf of Nadav Horesh Sent: Thu 04-Mar-10 11:55 To: Discussion of Numerical Python Subject: RE: [Numpy-discussion] multiprocessing shared arrays and numpy Maybe the attached file can help. Adpted and tested on amd64 linux Nadav -Original Message- From: numpy-discussion

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-04 Thread Nadav Horesh
Maybe the attached file can help. Adpted and tested on amd64 linux Nadav -Original Message- From: numpy-discussion-boun...@scipy.org on behalf of Nadav Horesh Sent: Thu 04-Mar-10 10:54 To: Discussion of Numerical Python Subject: Re: [Numpy-discussion] multiprocessing shared arrays and

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-03 Thread Nadav Horesh
There is a work by Sturla Molden: look for multiprocessing-tutorial.pdf and sharedmem-feb13-2009.zip. The tutorial includes what is dropped in the cookbook page. I am into the same issue and going to test it today. Nadav On Wed, 2010-03-03 at 15:31 +0100, Jesper Larsen wrote: > Hi people, > >

Re: [Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-03 Thread Francesc Alted
A Wednesday 03 March 2010 15:31:29 Jesper Larsen escrigué: > Hi people, > > I was wondering about the status of using the standard library > multiprocessing module with numpy. I found a cookbook example last > updated one year ago which states that: > > "This page was obsolete as multiprocessing'

[Numpy-discussion] multiprocessing shared arrays and numpy

2010-03-03 Thread Jesper Larsen
Hi people, I was wondering about the status of using the standard library multiprocessing module with numpy. I found a cookbook example last updated one year ago which states that: "This page was obsolete as multiprocessing's internals have changed. More information will come shortly; a link to t