[RFC v2 03/20] memory: merge adjacent segments of a single memory region

Avi Kivity
2011-06-27T13:22:14Z

Simple implementations of memory routers, for example the Cirrus VGA memory banks
or the 440FX PAM registers can generate adjacent memory regions which are contiguous.
Detect these and merge them; this saves kvm memory slots and shortens lookup times.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
memory.c | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/memory.c b/memory.c
index d962fff..f136714 100644
--- a/memory.c
+++ b/memory.c
@@ -122,6 +122,27 @@ static void flatview_destroy(FlatView *view)
qemu_free(view->ranges);
}

+/* Attempt to simplify a view by merging ajacent ranges */
+static void flatview_simplify(FlatView *view)
+{
+ unsigned i;
+ FlatRange *r1, *r2;
+
+ for (i = 0; i + 1 < view->nr; ++i) {
+ r1 = &view->ranges[i];
+ r2 = &view->ranges[i+1];
+ if (addrrange_end(r1->addr) == r2->addr.start
+ && r1->mr == r2->mr
+ && r1->offset_in_region + r1->addr.size == r2->offset_in_region
+ && r1->dirty_log_mask == r2->dirty_log_mask) {
+ r1->addr.size += r2->addr.size;
+ memmove(r2, r2 + 1, (view->nr - (i + 2)) * sizeof(*r2));
+ --view->nr;
+ --i;
+ }
+ }
+}
+
/* Render a memory region into the global view. Ranges in @view obscure
* ranges in @mr.
*/
@@ -209,6 +230,7 @@ static FlatView generate_memory_topology(MemoryRegion *mr)
flatview_init(&view);

render_memory_region(&view, mr, 0, addrrange_make(0, UINT64_MAX));
+ flatview_simplify(&view);

return view;
}
--
1.7.5.3