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memory: transaction API

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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