Matlab hangs with single-threaded code showing 1500% CPU usage

We have a 32 AMD core linux server. Matlab intermittently stops being single-threaded causing any calculations to stall (or at least to drastically slow). Top shows CPU usage in the range 1500-2400%. This behaviour is observed with matlab versions 2011b and 2012b. The stalling does not appear to be code dependent: it has happened on start-up, during long periods of idling, and during short periods of calculation. The behaviour persists whether or not the GUI is used. The behaviour does not appear to be reproducible.

Other servers running the same versions of the software, toolboxes etc. do not show the same behaviour. None of these have as many cores, and all are Intel.

I'd be very grateful if anybody can shed light on why this might be happening.

Answer 1

[Walter Roberson]

To be sure I understand: the problem does not happen on any of the intel-processor machines, but does happen on the AMD-processor machine?

Egads, my memory was right again! There have been AMD-specific reports, some of which had to do with BLAS,

http://www.mathworks.com/matlabcentral/newsreader/view_thread/161574

I can't tell you what I had for lunch yesterday, but 5 years later I can remember obscure pieces of technical information ?!

[Jamie]

Yes -- the problem happens only on the AMD-processor machine. Amazing memory for the BLAS reports! Is this still an issue? Both the Matlab versions and machine are comparatively new (the machine was bought less than a year ago), and I can't find any more recent AMD problems online.

[Walter Roberson]

I have no idea if it is still an issue. Once I had checked that our (then) server was Intel cpu, I did not have any further use for the information.