On 12.12.2017 15:29, Cornelia Huck wrote: > On Tue, 12 Dec 2017 15:13:46 +0100 > Christian Borntraeger <borntrae...@de.ibm.com> wrote: > >> On 12/12/2017 02:49 PM, Cornelia Huck wrote: > >>> One thing I noticed: You removed the caching of the flic (in the old >>> kvm inject routine), and you generally do more qom invocations (first, >>> to find the common flic; then, to translate to the qemu or kvm flic). >>> Not sure if this might be a problem (probably not). >> >> Is any of these calls on a potential fast path (e.g. guest without adapter >> interrupts)? If yes, then QOM is a no-go since it is really slow. > > At least the new airq interface was using QOM without caching before. > > It's basically about any interrupt; but otoh we are (for kvm) in > userspace already. Caching the flic and just keeping the casting to the > specialized flic might be ok (I'd guess that the lookup is the slowest > path.) >
Please note that the lookup is already cached in s390_get_flic(); That should be sufficient, as it does the expensive lookup. One cache should be enough, no? The other conversions should be cheap (and already were in place in a couple of places before). Thanks! -- Thanks, David / dhildenb
