From 4dc56152237f61694fa42675a78ffd14a509df98 Mon Sep 17 00:00:00 2001 From: Gonglei Date: Thu, 8 May 2014 11:47:32 +0800 Subject: [PATCH] memory: Don't update all memory region when ioeventfd changed memory mappings don't rely on ioeventfds, there is no need to destroy and rebuild them when manipulating ioeventfds, otherwise it scarifies performance. according to testing result, each ioeventfd deleing needs about 5ms, within which memory mapping rebuilding needs about 4ms. With many Nics and vmchannel in a VM doing migrating, there can be many ioeventfds deleting which increasing downtime remarkably. Signed-off-by: Gonglei Signed-off-by: Herongguang Signed-off-by: Paolo Bonzini --- memory.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) diff --git a/memory.c b/memory.c index 678661e2bb..829d56db37 100644 --- a/memory.c +++ b/memory.c @@ -28,6 +28,7 @@ static unsigned memory_region_transaction_depth; static bool memory_region_update_pending; +static bool ioeventfd_update_pending; static bool global_dirty_log = false; /* flat_view_mutex is taken around reading as->current_map; the critical @@ -786,22 +787,34 @@ void memory_region_transaction_begin(void) ++memory_region_transaction_depth; } +static void memory_region_clear_pending(void) +{ + memory_region_update_pending = false; + ioeventfd_update_pending = false; +} + void memory_region_transaction_commit(void) { AddressSpace *as; assert(memory_region_transaction_depth); --memory_region_transaction_depth; - if (!memory_region_transaction_depth && memory_region_update_pending) { - memory_region_update_pending = false; - MEMORY_LISTENER_CALL_GLOBAL(begin, Forward); + if (!memory_region_transaction_depth) { + if (memory_region_update_pending) { + MEMORY_LISTENER_CALL_GLOBAL(begin, Forward); - QTAILQ_FOREACH(as, &address_spaces, address_spaces_link) { - address_space_update_topology(as); + QTAILQ_FOREACH(as, &address_spaces, address_spaces_link) { + address_space_update_topology(as); + } + + MEMORY_LISTENER_CALL_GLOBAL(commit, Forward); + } else if (ioeventfd_update_pending) { + QTAILQ_FOREACH(as, &address_spaces, address_spaces_link) { + address_space_update_ioeventfds(as); + } } - - MEMORY_LISTENER_CALL_GLOBAL(commit, Forward); - } + memory_region_clear_pending(); + } } static void memory_region_destructor_none(MemoryRegion *mr) @@ -1373,7 +1386,7 @@ void memory_region_add_eventfd(MemoryRegion *mr, memmove(&mr->ioeventfds[i+1], &mr->ioeventfds[i], sizeof(*mr->ioeventfds) * (mr->ioeventfd_nb-1 - i)); mr->ioeventfds[i] = mrfd; - memory_region_update_pending |= mr->enabled; + ioeventfd_update_pending |= mr->enabled; memory_region_transaction_commit(); } @@ -1406,7 +1419,7 @@ void memory_region_del_eventfd(MemoryRegion *mr, --mr->ioeventfd_nb; mr->ioeventfds = g_realloc(mr->ioeventfds, sizeof(*mr->ioeventfds)*mr->ioeventfd_nb + 1); - memory_region_update_pending |= mr->enabled; + ioeventfd_update_pending |= mr->enabled; memory_region_transaction_commit(); }