I've noticed the BOINC has a problem with memory used calculations under
64-bit Windows, when running a mix of 32-bit workunits and 64-bit
workunits. It does not include the SYSWOW64 modules in use by the
32-bit workunits (possibly because they are listed as being run by
System and are not in the 32-bit memory space).
These SYSWOW64 modules roughly double the amount of 64-bit memory space
needed to run these 32-bit workunits.
As a result, a 64-bit workunit can check the memory available, decide
that it's enough, and start running. However, if the total RAM is 8 GB
or less, the doubling of space occupied by 32-bit workunits can exhaust
the free memory available in 64-bit memory space before the 64-bit
workunit reaches its first checkpoint, which puts the 64-bit workunit
into Waiting to run state and can also push it into virtual memory. If
Windows does not restore it to the same addresses in 64-bit memory when
restoring it from virtual memory (I believe I've read that it does not)
and the application is not sufficiently location-independent, BOINC will
restart this workunit from the beginning, and probably encounter the
same problem again, over and over.
Seen with:
64-bit Windows Vista Home Premium SP2 (some of the programs I run aren't
compatible with later Windows versions)
8 GB RAM, but BOINC limited to using 40% of it to avoid drastic
slowdowns of non-BOINC 32-bit programs, including one of the programs in
the path for accepting keyboard input; motherboard will not hold any
more RAM
BOINC 7.0.28, but also seen with some earlier 7.0.* versions; haven't
tried any versions after 7.0.28
A The Lattice Project workunit trying to use about 3.1 GB of 64-bit
memory, but also 32-bit workunits from other projects trying to use
about 300 MB of 32-bit memory (not counting the SYSWOW64 modules)
A possible fix I've thought of: Modify BOINC to use separate memory
limits for 64-bit memory space and for 32-bit memory space. Count the
32-bit workunits, but not the SYSWOW64 modules they use, against the
limit on 32-bit memory space. Count the 64-bit workunits, the 32-bit
workunits, and the SYSWOW64 modules used by the 32-bit workunits,
against the limit on 64-bit memory space.
I've seen nothing indicating whether 64-bit versions of Windows other
than Vista also need this fix, and nothing indicating whether 64-bit
operating systems other than Windows need it.
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