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memory: transaction API 

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 <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Avi Kivity 2011-07-26 14:26:13 +03:00 committed by Anthony Liguori
parent b8af1afbfb
commit 4ef4db8603
2 changed files with 26 additions and 0 deletions
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18
memory.c
View File

@ -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)

8
memory.h
View File

@ -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