On Monday 11 October 2010 12:11 pm, John Baldwin wrote: > 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.
When I wrote the code, generic_stop_cpus() didn't exist. Now it makes sense, though. > > 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. +1. Jung-uk Kim _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
