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[Qemu-devel] [PATCH] exec: avoid unnecessary cacheline bounce on ram_lis
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH] exec: avoid unnecessary cacheline bounce on ram_list.mru_block |
Date: |
Thu, 22 Oct 2015 13:51:30 +0200 |
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 <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
exec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/exec.c b/exec.c
index 54cd70a..439b128 100644
--- a/exec.c
+++ b/exec.c
@@ -860,7 +860,7 @@ static RAMBlock *qemu_get_ram_block(ram_addr_t addr)
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) {
--
2.5.0
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