On Tue, 2011-07-19 at 13:32 +0300, Avi Kivity wrote: > On 07/19/2011 01:17 PM, Sasha Levin wrote: > > On Tue, 2011-07-19 at 12:59 +0300, Avi Kivity wrote: > > > On 07/19/2011 12:53 PM, Sasha Levin wrote: > > > > > Make these per-guest instead of global. The lock may be contended, and > > > > > the list shouldn't hold items from different guests (why is it needed, > > > > > anyway?) > > > > > > > > > > > > > We only need the list for removal, since we only have the range we want > > > > to remove, and we want to find all devices which contain this range. > > > > > > > > > > All devices in the same guest which contain this range. Your patch > > > removes devices from all guests. > > > > > > > Yup. I've messed up guest-locality. Will fix. > > > > Also, I found this comment when increasing NR_IOBUS_DEVS: > > > > /* > > * It would be nice to use something smarter than a linear search, TBD... > > * Thankfully we dont expect many devices to register (famous last words :), > > * so until then it will suffice. At least its abstracted so we can change > > * in one place. > > */ > > > > Since so far we've registered 5-6 devices, and now it may increase > > significantly (since we may want to do the same change to ioeventfds, > > which work the same way) - how would you feel if we make devices > > register range(s) and do a rbtree lookup instead of a linear search? > > > > It makes sense. In fact your change is a good first step - so far it > was impossible to to a clever search since the seaching code was not > aware of the ranges (and could not be, since the single coalesced mmio > device had multiple ranges). > > Rather than an rbtree, I suggest putting all ranges in an array and > sorting it, then using binary search. > Why array over rbtree? An array would be heavier on register/unregister, and using rbtree would let us easily eliminate any max device limit we had so far. We've had good experience using interval rbtree in /tools/kvm where we did PIO and MMIO device mapping using an augmented rbtree which made range lookups very simple and fast. -- Sasha. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
