migration: Calculate ram size once

We are recalculating ram size continously, when we know that it don't
change during migration.  Create a field in RAMState to track it.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>

diff --git a/migration/ram.c b/migration/ram.c
index 1727fe5ef6d7ec04523268fdd7fd482cc09ffaee..6abfe075f2ac94ff8f1a9ee452adf64f08d5dfad 100644 (file)
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -330,6 +330,8 @@ struct RAMState {
     PageSearchStatus pss[RAM_CHANNEL_MAX];
     /* UFFD file descriptor, used in 'write-tracking' migration */
     int uffdio_fd;
+    /* total ram size in bytes */
+    uint64_t ram_bytes_total;
     /* Last block that we have visited searching for dirty pages */
     RAMBlock *last_seen_block;
     /* Last dirty target page we have sent */
@@ -2546,7 +2548,7 @@ static int ram_find_and_save_block(RAMState *rs)
     int pages = 0;
 
     /* No dirty page as there is zero RAM */
-    if (!ram_bytes_total()) {
+    if (!rs->ram_bytes_total) {
         return pages;
     }
 
@@ -3009,13 +3011,14 @@ static int ram_state_init(RAMState **rsp)
     qemu_mutex_init(&(*rsp)->bitmap_mutex);
     qemu_mutex_init(&(*rsp)->src_page_req_mutex);
     QSIMPLEQ_INIT(&(*rsp)->src_page_requests);
+    (*rsp)->ram_bytes_total = ram_bytes_total();
 
     /*
      * Count the total number of pages used by ram blocks not including any
      * gaps due to alignment or unplugs.
      * This must match with the initial values of dirty bitmap.
      */
-    (*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
+    (*rsp)->migration_dirty_pages = (*rsp)->ram_bytes_total >> TARGET_PAGE_BITS;
     ram_state_reset(*rsp);
 
     return 0;