[PATCH v1 1/5] kvm, memory: Optimize dirty page collection for dirty ring

[wucy11@chinatelecom.cn]

From: Chongyun Wu <wucy11@chinatelecom.cn>

When log_sync_global of dirty ring is called, it will collect
dirty pages on all cpus, including all dirty pages on memslot,
so when memory_region_sync_dirty_bitmap collects dirty pages
from KVM, this interface needs to be called once, instead of
traversing every dirty page. Each memslot is called once,
which is meaningless and time-consuming. So only need to call
log_sync_global once in memory_region_sync_dirty_bitmap.

Signed-off-by: Chongyun Wu <wucy11@chinatelecom.cn>
---
 softmmu/memory.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/softmmu/memory.c b/softmmu/memory.c
index 8060c6d..46c3ff9 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -2184,6 +2184,12 @@ static void memory_region_sync_dirty_bitmap(MemoryRegion *mr)
              */
             listener->log_sync_global(listener);
             trace_memory_region_sync_dirty(mr ? mr->name : "(all)", listener->name, 1);
+            /*
+             * The log_sync_global of the dirty ring will collect the dirty
+             * pages of all memslots at one time, so there is no need to
+             * call log_sync_global once when traversing each memslot.
+             */
+            break;
         }
     }
 }
-- 
1.8.3.1