On Tue, Sep 16, 2014 at 04:49:03PM -0700, Dave Hansen wrote: > On 09/16/2014 10:58 AM, Peter Zijlstra wrote: > > the 'problem' is that we currently have the static order of > > the masks, if we were to flip the MC and NUMA masks we need a condition > > to do that on and make sure everything is aware of that. > > > > CoD not being detectable sucks arse for sure :/ > > It's not like we can't detect it. We just can't detect it *explicitly*.
That's still suckage :-) > I think when we see nodes inside a package now, we have to trust that > they're OK. Its all we can do. > One other data point here. With an unpatched mainline, here's how the > sched domains look with cluster-on-die enabled: > > # grep . /proc/sys/kernel/sched_domain/cpu9/domain?/name > /proc/sys/kernel/sched_domain/cpu9/domain0/name:SMT // 2 threads > /proc/sys/kernel/sched_domain/cpu9/domain1/name:MC // 18 threads cores > /proc/sys/kernel/sched_domain/cpu9/domain2/name:NUMA // 36 threads > /proc/sys/kernel/sched_domain/cpu9/domain3/name:NUMA // 72 threads > > and with cluster-on-die disabled: > > # grep . /proc/sys/kernel/sched_domain/cpu9/domain?/name > /proc/sys/kernel/sched_domain/cpu9/domain0/name:SMT > /proc/sys/kernel/sched_domain/cpu9/domain1/name:MC > /proc/sys/kernel/sched_domain/cpu9/domain2/name:NUMA > > So, shockingly, the domains seem to be set up at at least conceptually > OK in both cases. Yeah, it works out by accident. It had to otherwise these patches wouldn't work. > We could probably rig up sched_init_numa() to mix topology levels > between the ones that come out of sched_domain_topology and the NUMA > levels, although that doesn't sound very appealing. > > Another option would be to: > 1. Add a new "PKG" level and actually _build_ it with phys_proc_id > 2. Make sure to tie the sysfs 'core_siblings' file to PKG > 3. Leave the "MC" level as it is now, but define it as being the lowest- > common-denominator of core grouping. In other words, the "MC" group > will stop at a NUMA node or a socket boundary, whichever it sees > first. > 4. Chop the "COD_NUMA" level off in sched_init_numa() No, we should provide an arch override for sched_domain_topology which has the right setup for the detected topology. See arm,powerpc and s390, which already have his. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
