[Qemu-devel] [PATCH 8/8] Maintain the number of dirty pages

[Juan Quintela]

Calculate the number of dirty pages takes a lot on hosts with lots
of memory.  Just maintain how many pages are dirty.

Signed-off-by: Juan Quintela <address@hidden>
---
 arch_init.c     |   15 +--------------
 cpu-all.h       |    1 +
 exec-obsolete.h |   10 ++++++++++
 3 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 7de1abf..545cf8f 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -228,20 +228,7 @@ static uint64_t bytes_transferred;

 static ram_addr_t ram_save_remaining(void)
 {
-    RAMBlock *block;
-    ram_addr_t count = 0;
-
-    QLIST_FOREACH(block, &ram_list.blocks, next) {
-        ram_addr_t addr;
-        for (addr = 0; addr < block->length; addr += TARGET_PAGE_SIZE) {
-            if (memory_region_get_dirty(block->mr, addr, TARGET_PAGE_SIZE,
-                                        DIRTY_MEMORY_MIGRATION)) {
-                count++;
-            }
-        }
-    }
-
-    return count;
+    return ram_list.dirty_pages;
 }

 uint64_t ram_bytes_remaining(void)
diff --git a/cpu-all.h b/cpu-all.h
index 50c8b62..88cedba 100644
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -477,6 +477,7 @@ typedef struct RAMBlock {
 typedef struct RAMList {
     uint8_t *phys_dirty;
     QLIST_HEAD(, RAMBlock) blocks;
+    uint64_t dirty_pages;
 } RAMList;
 extern RAMList ram_list;

diff --git a/exec-obsolete.h b/exec-obsolete.h
index f8ffce6..c099256 100644
--- a/exec-obsolete.h
+++ b/exec-obsolete.h
@@ -74,6 +74,11 @@ static inline int cpu_physical_memory_get_dirty(ram_addr_t 
start,
 static inline int cpu_physical_memory_set_dirty_flags(ram_addr_t addr,
                                                       int dirty_flags)
 {
+    if ((dirty_flags & MIGRATION_DIRTY_FLAG) &&
+        !cpu_physical_memory_get_dirty(addr, TARGET_PAGE_SIZE,
+                                       MIGRATION_DIRTY_FLAG)) {
+        ram_list.dirty_pages++;
+    }
     return ram_list.phys_dirty[addr >> TARGET_PAGE_BITS] |= dirty_flags;
 }

@@ -87,6 +92,11 @@ static inline int 
cpu_physical_memory_clear_dirty_flags(ram_addr_t addr,
 {
     int mask = ~dirty_flags;

+    if ((dirty_flags & MIGRATION_DIRTY_FLAG) &&
+        cpu_physical_memory_get_dirty(addr, TARGET_PAGE_SIZE,
+                                      MIGRATION_DIRTY_FLAG)) {
+        ram_list.dirty_pages--;
+    }
     return ram_list.phys_dirty[addr >> TARGET_PAGE_BITS] &= mask;
 }

-- 
1.7.10.2