Messages in this thread | | | Date | Tue, 28 Jun 2016 13:03:56 +0800 | From | Boqun Feng <> | Subject | Re: [PATCH 2/3] powerpc/spinlock: support vcpu preempted check |
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On Tue, Jun 28, 2016 at 11:39:18AM +0800, xinhui wrote: [snip] > > > +{ > > > + struct lppaca *lp = &lppaca_of(cpu); > > > + > > > + if (unlikely(!(lppaca_shared_proc(lp) || > > > + lppaca_dedicated_proc(lp)))) > > > > Do you want to detect whether we are running in a guest(ie. pseries > > kernel) here? Then I wonder whether "machine_is(pseries)" works here. > > > I tried as you said yesterday. but .h file has dependencies. > As you said, if we add #ifdef PPC_PSERIES, this is not a big problem. only powernv will be affected as they are built into same kernel img. >
I never said this it not a big problem ;-)
The problem here is that we only need to detect the vcpu preemption in a guest, and there could be several ways we can detect whether the kernel is running in a guest. It's worthwhile to try find the best one for this. Besides, it's really better that you can make sure we are runing out of options before you introduce something like lppaca_dedicated_proc().
I have a feeling that yield_count is non-zero only if we are running in a guest, if so, we can use this and save several loads. But surely we need the confirmation from ppc maintainers.
Regards, Boqun [unhandled content-type:application/pgp-signature] | |