On 10/25/2012 07:13 PM, Peter Maydell wrote: > On 25 October 2012 18:07, Avi Kivity <a...@redhat.com> wrote: >> On 10/25/2012 04:04 PM, Peter Maydell wrote: >>> Is there a clear up to date description somewhere of the design and >>> locking strategy here somewhere? I'd rather not have to try to >>> reconstitute it by reading the whole patchset... >> >> It was described somewhere in a document by Marcelo and myself. >> Basically the goal is to arrive at >> >> address_space_write(): >> rcu_read_lock() >> mr = lookup() >> mr->ref() >> rcu_read_unlock() >> >> mr->dispatch() >> >> mr->unref() >> >> This is the same strategy used in many places in the kernel. > > Yes, but this is rather short on the details
Until Jan fleshes this out: > (eg, does every > device have its own lock, No, devices which are not modified will continue to use the BQL. > what are we doing with irqs, Eventually they will gain fine-grained threading too. Until then, they will be protected by the big lock (and any device which calls any irq APIs must hold it). > how about > dma from devices, etc etc). DMA will be unlocked, if done to a device which has its own lock (same as mmio). > It's the details of the design I'd > like to see described... -- error compiling committee.c: too many arguments to function
