[Qemu-devel] [PATCH 39/39] migration: synchronize memory bitmap 64bits at a time

[Juan Quintela <quintela@redhat.com>]

We use the old code if the bitmaps are not aligned

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 arch_init.c | 43 ++++++++++++++++++++++++++++++++++---------
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index fe88d64..0909531 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -50,6 +50,7 @@
 #include "exec/cpu-all.h"
 #include "exec/memory-physical.h"
 #include "hw/acpi/acpi.h"
+#include "qemu/host-utils.h"

 #ifdef DEBUG_ARCH_INIT
 #define DPRINTF(fmt, ...) \
@@ -376,15 +377,37 @@ static inline bool migration_bitmap_set_dirty(ram_addr_t addr)
 static void migration_bitmap_sync_range(ram_addr_t start, ram_addr_t length)
 {
     ram_addr_t addr;
-
-    for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
-        if (cpu_physical_memory_get_dirty(start + addr,
-                                          TARGET_PAGE_SIZE,
-                                          DIRTY_MEMORY_MIGRATION)) {
-            cpu_physical_memory_reset_dirty(start + addr,
-                                            TARGET_PAGE_SIZE,
-                                            DIRTY_MEMORY_MIGRATION);
-            migration_bitmap_set_dirty(start + addr);
+    unsigned long page = BIT_WORD(start >> TARGET_PAGE_BITS);
+
+    /* start address is aligned at the start of a word? */
+    if (((page * BITS_PER_LONG) << TARGET_PAGE_BITS) == start) {
+        int k;
+        int nr = BITS_TO_LONGS(length >> TARGET_PAGE_BITS);
+        unsigned long *src = ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION];
+
+        printf("XXXX:optimized start %lx page %lx length %lu\n", start, page, length);
+
+        for (k = page; k < page + nr; k++) {
+            if (src[k]) {
+                unsigned long new_dirty;
+                new_dirty = ~migration_bitmap[k];
+                migration_bitmap[k] |= src[k];
+                new_dirty &= src[k];
+                migration_dirty_pages += ctpopl(new_dirty);
+                src[k] = 0;
+            }
+        }
+    } else {
+        printf("XXXX:not optimized start %lx length %lu\n", start, length);
+        for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
+            if (cpu_physical_memory_get_dirty(start + addr,
+                                              TARGET_PAGE_SIZE,
+                                              DIRTY_MEMORY_MIGRATION)) {
+                cpu_physical_memory_reset_dirty(start + addr,
+                                                TARGET_PAGE_SIZE,
+                                                DIRTY_MEMORY_MIGRATION);
+                migration_bitmap_set_dirty(start + addr);
+            }
         }
     }
 }
@@ -415,6 +438,8 @@ static void migration_bitmap_sync(void)
     address_space_sync_dirty_bitmap(&address_space_memory);

     QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+        printf("XXXX: name %s addr %lx length %lu\n",
+               block->idstr, block->mr->ram_addr, block->length);
         migration_bitmap_sync_range(block->mr->ram_addr, block->length);
     }
     trace_migration_bitmap_sync_end(migration_dirty_pages
-- 
1.8.3.1