On 25/01/18 16:31, Jan Beulich wrote: >>>> On 25.01.18 at 17:09, <andrew.coop...@citrix.com> wrote: >> On 25/01/18 15:57, Jan Beulich wrote: >>>>>> On 24.01.18 at 14:12, <andrew.coop...@citrix.com> wrote: >>>> @@ -1743,6 +1744,34 @@ void context_switch(struct vcpu *prev, struct vcpu >>>> *next) >>>> } >>>> >>>> ctxt_switch_levelling(next); >>>> + >>>> + if ( opt_ibpb && !is_idle_domain(nextd) ) >>> Is the idle domain check here really useful? >> Yes, because as you pointed out in v9, the outer condition isn't >> sufficient to exclude nextd being idle. > True, but then again - what's wrong with an idle vCPU making it > into the block? It'll be a pointless barrier that you issue, but no > other harm afaics. Remember that I complained about the missing > check only because of the chosen variable naming, but you've > renamed the variables in question, so I don't see why you've also > added the extra condition.
The barrier would be pointless, yes, but at 8k cycles, the cost is massive. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
