[Qemu-devel] [PATCH] migration: cache memory region ram ptr

[Peter Lieven <pl@kamp.de>]

we currently look up the ram ptr for each single page. Cache
the pointer while we operate on the same block.

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 arch_init.c |   23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 582b716..ce338aa 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -594,13 +594,19 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
                 ram_bulk_stage = false;
             }
         } else {
+            static uint8_t *ram_ptr;
             int ret;
             uint8_t *p;
             bool send_async = true;
-            int cont = (block == last_sent_block) ?
-                RAM_SAVE_FLAG_CONTINUE : 0;
+            int cont = 0;
 
-            p = memory_region_get_ram_ptr(mr) + offset;
+            if (block != last_sent_block) {
+                ram_ptr = memory_region_get_ram_ptr(mr);
+            } else {
+                cont = RAM_SAVE_FLAG_CONTINUE;
+            }
+
+            p = ram_ptr + offset;
 
             /* In doubt sent page as normal */
             bytes_sent = -1;
@@ -990,16 +996,17 @@ static inline void *host_from_stream_offset(QEMUFile *f,
                                             int flags)
 {
     static RAMBlock *block = NULL;
+    static uint8_t *ram_ptr;
     char id[256];
     uint8_t len;
 
     if (flags & RAM_SAVE_FLAG_CONTINUE) {
-        if (!block) {
+        if (!block || !ram_ptr) {
             fprintf(stderr, "Ack, bad migration stream!\n");
             return NULL;
         }
 
-        return memory_region_get_ram_ptr(block->mr) + offset;
+        return ram_ptr + offset;
     }
 
     len = qemu_get_byte(f);
@@ -1007,8 +1014,10 @@ static inline void *host_from_stream_offset(QEMUFile *f,
     id[len] = 0;
 
     QTAILQ_FOREACH(block, &ram_list.blocks, next) {
-        if (!strncmp(id, block->idstr, sizeof(id)))
-            return memory_region_get_ram_ptr(block->mr) + offset;
+        if (!strncmp(id, block->idstr, sizeof(id))) {
+            ram_ptr = memory_region_get_ram_ptr(block->mr);
+            return ram_ptr + offset;
+        }
     }
 
     fprintf(stderr, "Can't find block %s!\n", id);
-- 
1.7.9.5