On 06/27/2012 07:27 PM, Jan Kiszka wrote: > Changes in v2: > - added memory_region_clear_flush_coalesced > - call memory_region_clear_flush_coalesced from > memory_region_clear_coalescing > - wrap all region manipulations via memory_region_transaction_begin/ > commit internally > - flush coalesced MMIO only on memory_region_transaction_begin > > Original description: > > We currently flush the coalesced MMIO buffer on every vmexit to > userspace. KVM only provides a single buffer per VM, so a central lock > is required to read from it. This is a contention point given a large > enough VCPU set. Moreover, we need to hold the BQL while replaying the > queued requests, probably for a long time until there is more fine > grained locking available. Good reasons to overcome the unconditional > flush. > > The series achieves this by flushing only on selected memory region > accesses, either generically via the memory access dispatcher or > directly on certain VGA PIO accesses that are not yet fully converted. > Another reason to flush are remappings or other relevant region state > changes.
Looks good; please see minor comment on patch 2. -- error compiling committee.c: too many arguments to function
