From e87c099f1c9e461dcaa093b1b40b14e7e899e70f Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 14 Sep 2011 12:16:20 +0300 Subject: [PATCH] memory: optimize empty transactions due to mutators 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 --- memory.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/memory.c b/memory.c index 7e842b3ad..87639ab6e 100644 --- a/memory.c +++ b/memory.c @@ -19,6 +19,7 @@ #include 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) -- 2.39.5