From 544cff46c018036cd66e98ffb224dd9f098065c8 Mon Sep 17 00:00:00 2001 From: hongmianquan Date: Wed, 30 Aug 2023 11:29:06 +0800 Subject: memory: avoid updating ioeventfds for some address_space When updating ioeventfds, we need to iterate all address spaces, but some address spaces do not register eventfd_add|del call when memory_listener_register() and they do nothing when updating ioeventfds. So we can skip these AS in address_space_update_ioeventfds(). The overhead of memory_region_transaction_commit() can be significantly reduced. For example, a VM with 8 vhost net devices and each one has 64 vectors, can reduce the time spent on memory_region_transaction_commit by 20%. Message-ID: <20230830032906.12488-1-hongmianquan@bytedance.com> Reviewed-by: Peter Xu Signed-off-by: hongmianquan Signed-off-by: David Hildenbrand --- include/exec/memory.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/exec') diff --git a/include/exec/memory.h b/include/exec/memory.h index cc68249eda..ef23d65afc 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -1095,6 +1095,7 @@ struct AddressSpace { struct FlatView *current_map; int ioeventfd_nb; + int ioeventfd_notifiers; struct MemoryRegionIoeventfd *ioeventfds; QTAILQ_HEAD(, MemoryListener) listeners; QTAILQ_ENTRY(AddressSpace) address_spaces_link; -- cgit 1.4.1