Re: Memory Exclusion

From: Chris Chaudoir (
Date: Fri Nov 13 2009 - 10:56:23 PST

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    Thanks for the info...any advice on where is the best place to jump into the
    source code?
    On Tue, Nov 10, 2009 at 4:02 PM, Paul H. Hargrove <PHHargrove_at_lbl_dot_gov>wrote:
    > Chris,
    > Currently BLCR will exclude :
    > 1) Pages mapped from a file and unmodified, which will include the code and
    > read-only data segments of the executable and shared libraries.  This may
    > also included mmap()s performed by the application, if any.
    > 2) "Anonymous" (non file-backed) pages that are mapped in to the process
    > but not yet written to, which includes unused portions of the stack and
    > heap.
    > In the next release (target Jan 2010) we will have a mechanism that allows
    > applications and libraries to hint to BLCR about regions of memory that can
    > be excluded.  For instance, the OpenMPI developer that works on
    > checkpoint/restart has suggested that they might exclude any of MPI's
    > receive buffers that don't hold actual messages at the time the checkpoint
    > is taken.
    > We are also working on incremental checkpointing for the next release.  In
    > the case where one takes multiple checkpoints of the same process over time,
    > this will omit from a checkpoint any pages not written to since the previous
    > one.  However, when using this mechanism one needs all the past checkpoints
    > to restore (and so more disk space is required).
    > -Paul
    > Chris Chaudoir wrote:
    >> To Paul et all,
    >>  I just started playing around with the latest version of BLCR (nice btw)
    >> and had a question...besides the expected methods of skipping the code and
    >> unused stack, can you describe the 'memory exclusion' methods in BLCR (or
    >> point me to the right documentation)?
    >>   Respectfully,
    >>  Chris Chaudoir
    >>  BSEE & CS grad student
    > --
    > Paul H. Hargrove                          PHHargrove_at_lbl_dot_gov
    > Future Technologies Group                 Tel: +1-510-495-2352
    > HPC Research Department                   Fax: +1-510-486-6900
    > Lawrence Berkeley National Laboratory

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