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[Qemu-devel] [PATCH 4/7] memory: optimize empty transactions due to muta
From: |
Avi Kivity |
Subject: |
[Qemu-devel] [PATCH 4/7] memory: optimize empty transactions due to mutators |
Date: |
Thu, 15 Dec 2011 17:18:36 +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] [PULL v3 0/7] Memory API mutators, Avi Kivity, 2011/12/15
- [Qemu-devel] [PATCH 3/7] memory: introduce memory_region_set_alias_offset(), Avi Kivity, 2011/12/15
- [Qemu-devel] [PATCH 2/7] memory: introduce memory_region_set_address(), Avi Kivity, 2011/12/15
- [Qemu-devel] [PATCH 4/7] memory: optimize empty transactions due to mutators,
Avi Kivity <=
- [Qemu-devel] [PATCH 7/7] docs: document memory API interaction with migration, Avi Kivity, 2011/12/15
- [Qemu-devel] [PATCH 6/7] piix_pci: adapt smram mapping to use memory mutators, Avi Kivity, 2011/12/15
- [Qemu-devel] [PATCH 5/7] cirrus_vga: adapt to memory mutators API, Avi Kivity, 2011/12/15
- [Qemu-devel] [PATCH 1/7] memory: introduce memory_region_set_enabled(), Avi Kivity, 2011/12/15
- Re: [Qemu-devel] [PULL v3 0/7] Memory API mutators, Anthony Liguori, 2011/12/19