exec: avoid unnecessary cacheline bounce on ram_list.mru_block
Whenever the MRU cache hits for the list of RAM blocks, qemu_get_ram_block
does an unnecessary write that causes a processor cache line to bounce
from one core to another. This causes a performance hit.
Reported-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
diff --git a/exec.c b/exec.c
index ed88e72..a028961 100644
--- a/exec.c
+++ b/exec.c
@@ -903,7 +903,7 @@
block = atomic_rcu_read(&ram_list.mru_block);
if (block && addr - block->offset < block->max_length) {
- goto found;
+ return block;
}
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
if (addr - block->offset < block->max_length) {
