From: Chaney, Ben <bchaney@akamai.com>
Date: Mon, 16 Jun 2025 20:56:50 +0000 (+0000)
Subject: migration: Don't sync volatile memory after migration completes
X-Git-Tag: v7.2.19~10
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=94ab5f6743b6d56f8ff6366ebde42e62e93b517d;p=thirdparty%2Fqemu.git

migration: Don't sync volatile memory after migration completes

Syncing volatile memory provides no benefit, instead it can cause
performance issues in some cases.  Only sync memory that is marked as
non-volatile after migration completes on destination.

Signed-off-by: Ben Chaney <bchaney@akamai.com>
Fixes: bd108a44bc29 (migration: ram: Switch to ram block writeback)
Link: https://lore.kernel.org/r/1CC43F59-336F-4A12-84AD-DB89E0A17A95@akamai.com
Signed-off-by: Peter Xu <peterx@redhat.com>
(cherry picked from commit 983899eab4939dc4dff67fa4d822c5b4df7eae21)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---

diff --git a/migration/ram.c b/migration/ram.c
index f25ebd9620d..e3ab67acd43 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3930,7 +3930,9 @@ static int ram_load_cleanup(void *opaque)
     RAMBlock *rb;
 
     RAMBLOCK_FOREACH_NOT_IGNORED(rb) {
-        qemu_ram_block_writeback(rb);
+        if (memory_region_is_nonvolatile(rb->mr)) {
+            qemu_ram_block_writeback(rb);
+        }
     }
 
     xbzrle_load_cleanup();