On Tue, 2017-04-11 at 14:28 +0200, Cédric Le Goater wrote: > I really don't know. > > Ben, now that we have mttcg activated by default on ppc, it takes > a while for the linux kernel to do the early setup. I think we are > in the code section where we spin loop the secondaries. Most of the > time is spent in skiboot under cpu_idle/relax. > > Any idea where that could come from ? > > > See c22edfebff29f63d793032e4fbd42a035bb73e27 for an example. > > Thanks for the hint.
They are spinning, but they have smt_low instructions in the loop, maybe that causes us to do some kind of synchronization as we exit the emulation loop on these ? I added that to force relinguish time to other threads on the pre-MT TCG... There isn't really such a "pause" instruction. At least not yet.... P9 has a wait that is meant to wait for special AS_Notify cycles but will also wait for interrupts. We don't have an mwait at this point. Ben.
