Allow changes to the memory hierarchy to be accumulated and
made visible all at once. This reduces computational effort,
especially when an accelerator (e.g. kvm) is involved.
Useful when a single register update causes multiple changes
to an address space.
Signed-off-by: Avi Kivity <a...@redhat.com>
---
memory.c | 18 ++++++++++++++++++
memory.h | 8 ++++++++
2 files changed, 26 insertions(+), 0 deletions(-)
diff --git a/memory.c b/memory.c
index 7a5670e..5c6e63d 100644
--- a/memory.c
+++ b/memory.c
@@ -18,6 +18,8 @@
#include "kvm.h"
#include <assert.h>
+unsigned memory_region_transaction_depth = 0;
+
typedef struct AddrRange AddrRange;
struct AddrRange {
@@ -626,6 +628,10 @@ static void address_space_update_topology(AddressSpace *as)
static void memory_region_update_topology(void)
{
+ if (memory_region_transaction_depth) {
+ return;
+ }
+
if (address_space_memory.root) {
address_space_update_topology(&address_space_memory);
}
@@ -634,6 +640,18 @@ static void memory_region_update_topology(void)
}
}
+void memory_region_transaction_begin(void)
+{
+ ++memory_region_transaction_depth;
+}
+
+void memory_region_transaction_commit(void)
+{
+ assert(memory_region_transaction_depth);
+ --memory_region_transaction_depth;
+ memory_region_update_topology();
+}
+
void memory_region_init(MemoryRegion *mr,
const char *name,
uint64_t size)
diff --git a/memory.h b/memory.h
index c280a39..4e518b2 100644
--- a/memory.h
+++ b/memory.h
@@ -456,6 +456,14 @@ void memory_region_add_subregion_overlap(MemoryRegion *mr,
void memory_region_del_subregion(MemoryRegion *mr,
MemoryRegion *subregion);
+/* Start a transaction; changes will be accumulated and made visible only
+ * when the transaction ends.
+ */
+void memory_region_transaction_begin(void);
+/* Commit a transaction and make changes visible to the guest.
+ */
+void memory_region_transaction_commit(void);
+
#endif
#endif
--
1.7.5.3
