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Problems (view source)

Revision as of 19:56, 10 February 2016

1,809 bytes removed ,  10 February 2016
remove text referring to 32bit binary
(remove text referring to 32bit binary)
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The numbers above mean a 10-fold increase over the default, and should be enough. I've found this to be necessary for unusually large frames (32 MB).
The numbers above mean a 10-fold increase over the default, and should be enough. I've found this to be necessary for unusually large frames (32 MB).
xds_par in this case also might need an increase of the environment variable OMP_STACKSIZE (e.g. "setenv OMP_STACKSIZE 128M").
xds_par in this case also might need an increase of the environment variable OMP_STACKSIZE (e.g. "setenv OMP_STACKSIZE 128M").
=== memory consumption exceeding the 4GB barrier when using the 32bit binary ===
As pointed out by James Holton, the memory consumed by huge frames in combination with many threads may be larger than 32 bits allow. Execution then stops with
forrtl: severe (41): insufficient virtual memory
The workaround is to limit the [http://homes.mpimf-heidelberg.mpg.de/~kabsch/xds/html_doc/xds_parameters.html MAXIMUM_NUMBER_OF_PROCESSORS], or to use XDS instead of XDS_PAR. An even better solution is to switch to the 64bit binary, but that of course requires a 64bit operating system.


=== Problems with OpenMP ===
=== Problems with OpenMP ===
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If the "xds_par" binary crashed, try "xds". xds_par uses OpenMP for parallelization, which adds complexity. If it works with xds, but not with xds_par, then there is a chance that some environment variable needs to be set/changed. In any case the XDS developers would like to learn about this.
If the "xds_par" binary crashed, try "xds". xds_par uses OpenMP for parallelization, which adds complexity. If it works with xds, but not with xds_par, then there is a chance that some environment variable needs to be set/changed. In any case the XDS developers would like to learn about this.


=== limitation of the parallel 32bit binary  ===
=== 64bit binary on a 32bit operating system ===
 
The 32bit OpenMP binary may not be able to allocate enough storage when using many threads (e.g. >10). The error message might be something like:
 
OMP: Error #34: System unable to allocate necessary resources for OMP thread:
OMP: System error #11: Resource temporarily unavailable
 
=== 64bit binary on a 32 bit operating system ===


If the error message is e.g.
If the error message is e.g.
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or
or
  -bash: /usr/local/bin/xds: cannot execute binary file
  -bash: /usr/local/bin/xds: cannot execute binary file
make sure to use the 32bit version of XDS instead - you try to run the 64bit version on a 32bit operating system; this won't work.
you try to run the 64bit version on a 32bit operating system; this won't work. Since October 2015, you need a 64bit Linux operating system to run XDS because the 32bit version is no longer provided.
 
=== CPU without SSE2 support ===
 
If the error message is
 
forrtl: severe (168): Program Exception - illegal instruction
Image              PC        Routine            Line        Source
xds                08055250  Unknown              Unknown  Unknown
xds                0804B3F6  Unknown              Unknown  Unknown
 
this means that unfortunately the CPU of your machine is too old to be supported by XDS (which in this respect is compiled with the default options of the ifort compiler). This may happen e.g. with old AMD CPUs that don't support SSE2 (on Linux check the ''flags'' field of /proc/cpuinfo for the presence of the sse2 flag).


According to [http://en.wikipedia.org/wiki/SSE2#Notable_IA-32_CPUs_not_supporting_SSE2] the following Intel-compatible CPUs did not implement SSE2 after SSE2 was introduced (2001):
* AMD CPUs prior to Athlon 64, including all Socket A-based CPUs
* Intel CPUs prior to Pentium 4
* VIA C3
* Transmeta Crusoe


=== ASSERT VIOLATION ===
=== ASSERT VIOLATION ===
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