Hi Alvaro,
Thanks for agreeing to share this dialogue with the dmtcp-forum.
It may help other users looking for information.
If I understand correctly, you should be able to use the technique
mentioned in
http://dmtcp.sourceforge.net/FAQ.html#size
But maybe I'm still not understanding what you want to do.
Best,
- Gene
----- Original Message -----
From: Alvaro Wong <wonb...@gmail.com>
To: Gene Cooperman <g...@ccs.neu.edu>
Cc: Kapil Arya <ka...@ccs.neu.edu>
Sent: Fri, 29 May 2015 14:36:25 -0400 (EDT)
Subject: Re: Question about DMTCP
Hi Gene, sure you can put it in the dmtcp-forum. I know that you really
detect the zeros. Actually, i am able to detect the pages that the
application uses for a segment of execution. But i want to change the
values (to zero) of the memory pages that the application didn't use in a
segment (phase, function) of execution (inside the vector or array where
the dmtcp save the maps), before that the dtmcp writes the checkpoint.
Best Regards
Alvaro
On Fri, May 29, 2015 at 8:10 PM, Gene Cooperman <g...@ccs.neu.edu> wrote:
> Kapil (and Alvaro),
> Isn't it true that DMTCP already detects zero pages and replaces
> them with a special marker in order to reduce the checkpoint size?
>
> Alvaro,
> If you are concerned about checkpoint image size, here are some
> things that you can think about. First, the checkpoint image file
> is just a gzip-compressed version of the original data in memory,
> plus some minor headers. If you want to test this, try:
> util/readdmtcp.sh ckpt_a.out_*.dmtcp
> Also, try:
> mv ckpt_a.out_*.dmtcp ckpt_a.out.dmtcp.gz
> gunzip ckpt_a.out.dmtcp.gz
> ls -l ckpt_a.out.dmtcp
> That should tell you the size of the memory image in RAM that was save in
> the
> checkpoint image. I believe that we detect zero pages, and do not
> save the many zeroes. Also, see:
> http://dmtcp.sourceforge.net/FAQ.html#size
> for a related question on the DMTCP FAQ.
>
> Alvaro,
> Do you have any objection if I copy this e-mail to dmtcp-forum?
> This seems like the type of information that other users would benefit
> from, and this will help Google to find the information.
>
> Thanks,
> - Gene
>
> On Fri, May 29, 2015 at 09:08:28AM -0400, Kapil Arya wrote:
> > Hi Alvaro,
> >
> > The file is src/writeckpt.cpp. Please search for "writememoryarea" and
> that
> > will provide you with proper function.
> >
> > Kapil
> >
> >
> > On Fri, May 29, 2015 at 5:47 AM, Alvaro Wong <wonb...@gmail.com> wrote:
> >
> > > Hi, 'Im Alvaro from University of Autonomy of Barcelona, i'm trying to
> > > find the file (code) of the dmtcp that save the memory pages of the
> > > program. The goal is try to fill with zero the memory pages that the
> > > program do not use in a specific segment of the execution in order to
> > > reduce the checkpoint size when it is compressed.
> > >
> > >
> > > Best regards,
> > > Alvaro
------------------------------------------------------------------------------
_______________________________________________
Dmtcp-forum mailing list
Dmtcp-forum@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/dmtcp-forum
