On Tue, Oct 29, 2013 at 09:00:52AM +0530, Preeti U Murthy wrote: > > Oh nice, that gets rid of the multiple atomics, and it nicely splits > > this nohz logic into per topology groups -- now if only we could split > > the rest too :-) > > I am sorry, I don't get you here. By the 'rest', do you refer to > nohz_kick_needed() as below? Or am I missing something?
Nah, the rest of the NOHZ infrastructure. Currently its global state; there were some patches a few years ago that attempted to make that per-node state, but that work stalled due to people switching jobs. > >> + sd = highest_flag_domain(cpu, SD_ASYM_PACKING); > >> + > >> + if (sd && (cpumask_first_and(nohz.idle_cpus_mask, > >> + sched_domain_span(sd)) < cpu)) > >> + goto need_kick_unlock; > >> + > >> rcu_read_unlock(); > >> return 0; > > > > This again is a bit sad; most archs will not have SD_ASYM_PACKING set at > > all; this means that they all will do a complete (and pointless) sched > > domain tree walk here. > > There will not be a 'complete' sched domain tree walk right? The > iteration will break at the first level of the sched domain for those > archs which do not have SD_ASYM_PACKING set at all. Ah indeed; I think I got confused due to me modifying highest_flag_domain() earlier to assume a flag is carried from the lowest domain upwards. > But it is true that doing a sched domain tree walk regularly is a bad > idea, might as well update the domain with SD_ASYM_PACKING flag set once > and query this domain when required. > > I will send out the patch with sd_asym domain introduced rather than the > above. Thanks _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
