On 07/11/2014 10:29, Andrew Jones wrote: >> > I think this would cause too many failures in the wild. Perhaps error >> > out if it is lower, and warn if sockets * cores * threads > max_cpus >> > since we actually allow hot-plug a thread at a time? > We'd still have more failures if we choose to error out when it's lower, > since we currently silently adjust threads in some of those cases, or > just don't care that the topology doesn't support up to maxcpus in other.
So I guess we need a decent fallback if it doesn't match. Something like (based also on the reply from Eduardo): 1) always warn if max_cpus % (cores*threads) != 0 || smp_cpus % (cores*threads) != 0 2) if sockets*cpus*threads < max_cpus, adjust sockets to DIV_ROUND_UP(max_cpus, cores*threads). If we didn't warn in step 1, do it now. Give a different, less harsh warning if the cmdline sockets*cpus*threads did match smp_cpus. In the latter case, the user _almost_ knows what he was doing. Not perfect, but it could be something to start from. Adjusting sockets is better than adjusting threads. Paolo > I'm not sure how best to go about modifying the command line semantics > in a backwards compatible way, other than to just create a new "-smp" > option. I'm open to all opinions and suggestions.
