On Thursday, October 07, 2010 1:53:46 pm Andriy Gapon wrote: > > Here is patch that applies the technique from panic() to generic_stop_cpus() > to > prevent its parallel execution on multiple CPUs: > http://people.freebsd.org/~avg/generic_stop_cpus.diff > > In theory this could lead to two CPUs stopping each other and everyone else, > and > thus a total system halt. > > Also, in theory, we should have some smarter locking here, because two (or > more > CPUs) could be stopping unrelated sets of CPUs. But in practice, it seems, > this > function is only used to stop "all other" CPUs. Unless I overlooked other > usages, > that is. > > Additionally, I took this opportunity to make amd64-specific suspend_cpus() > function use generic_stop_cpus() instead of rolling out essentially duplicate > code. I couldn't see any reason no to consolidate, but perhaps I missed > something. > > Big thanks to Matthew and his employer for the idea and example.
One note. Use 'cpu_spinwait()' in the inner loop waiting for 'stopping_cpu' to change. -- John Baldwin _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[email protected]"
