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[Qemu-devel] [PATCH v2 4/6] memory: optimize empty transactions due to m
From: |
Avi Kivity |
Subject: |
[Qemu-devel] [PATCH v2 4/6] memory: optimize empty transactions due to mutators |
Date: |
Sun, 4 Dec 2011 20:09:39 +0200 |
The mutating memory APIs can easily cause empty transactions,
where the mutators don't actually change anything, or perhaps
only modify disabled regions. Detect these conditions and
avoid regenerating the memory topology.
Signed-off-by: Avi Kivity <address@hidden>
---
memory.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/memory.c b/memory.c
index 7e842b3..87639ab 100644
--- a/memory.c
+++ b/memory.c
@@ -19,6 +19,7 @@
#include <assert.h>
unsigned memory_region_transaction_depth = 0;
+static bool memory_region_update_pending = false;
typedef struct AddrRange AddrRange;
@@ -757,6 +758,7 @@ static void address_space_update_topology(AddressSpace *as)
static void memory_region_update_topology(MemoryRegion *mr)
{
if (memory_region_transaction_depth) {
+ memory_region_update_pending |= !mr || mr->enabled;
return;
}
@@ -770,6 +772,8 @@ static void memory_region_update_topology(MemoryRegion *mr)
if (address_space_io.root) {
address_space_update_topology(&address_space_io);
}
+
+ memory_region_update_pending = false;
}
void memory_region_transaction_begin(void)
@@ -781,7 +785,9 @@ void memory_region_transaction_commit(void)
{
assert(memory_region_transaction_depth);
--memory_region_transaction_depth;
- memory_region_update_topology(NULL);
+ if (!memory_region_transaction_depth && memory_region_update_pending) {
+ memory_region_update_topology(NULL);
+ }
}
static void memory_region_destructor_none(MemoryRegion *mr)
--
1.7.7.1
- [Qemu-devel] [PATCH v2 0/6] Memory API mutators, Avi Kivity, 2011/12/04
- [Qemu-devel] [PATCH v2 4/6] memory: optimize empty transactions due to mutators,
Avi Kivity <=
- [Qemu-devel] [PATCH v2 2/6] memory: introduce memory_region_set_address(), Avi Kivity, 2011/12/04
- [Qemu-devel] [PATCH v2 6/6] piix_pci: adapt smram mapping to use memory mutators, Avi Kivity, 2011/12/04
- [Qemu-devel] [PATCH v2 3/6] memory: introduce memory_region_set_alias_offset(), Avi Kivity, 2011/12/04
- [Qemu-devel] [PATCH v2 1/6] memory: introduce memory_region_set_enabled(), Avi Kivity, 2011/12/04
- [Qemu-devel] [PATCH v2 5/6] cirrus_vga: adapt to memory mutators API, Avi Kivity, 2011/12/04
- Re: [Qemu-devel] [PATCH v2 0/6] Memory API mutators, Anthony Liguori, 2011/12/07