On 2018-04-11 12:05, Achim Gratz wrote: > I seem to be the first to try Cygwin on a box that has multiple > processor groups, which seems odd. Anyway, I've already noticed two > more things that indicate that Cygwin and/or Cygwin applications > currently don't deal well with the situation: > > 1. Trying to run top, it shows only the first 16 processors and then > exits with an error that "openproc failed". Interestingly enough it > will keep running despite this error when running under strace (still > only showing the processors from one group, presumably the one that top > got started in). > > 2. Git will correctly determine that it can use 32 threads for garbage > collection, but it starts them all in the same processor group. > > The problem here is that on Linux you don't need to do anything extra to > use any of the advertised logical processors from a single application, > while on Windows you need to first create a thread and set it's affinity > to a different group than where your process was started in, then assign > each new thread an affinity to one of the available groups. If you > don't do that, all threads will be restricted to the original group. > > > Some more info on these differences (and already a bit outdated > w.r.t. the way processor groups are formed): > > https://software.intel.com/en-us/blogs/2010/12/16/tbb-30-high-end-many-cores-and-windows-processor-groups > > If it would be possible for Cygwin to hide that ugliness from Cygwin > applications I think that'd be highly welcome. Otherwise there might > need to be some option to restrict Cygwin to a single processor group > for some applications to work (correctly).
Have you tried installing and running hwloc package to find out how it sees your system? If you run lstopo under X, you get a pretty diagram, but you can also run lstopo-no-graphics aka hwloc-ls without X. Running "apropos hwloc" lists commands you can use to manipulate the topology. -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
