Am 28.06.2016 um 12:43 schrieb Paolo Bonzini:
On 28/06/2016 11:01, Peter Lieven wrote:
this was causing serious framentation in conjunction with the
subpages since RCU was introduced. The node space was allocated
at approx 32kB then reallocted to approx 75kB and this a few hundred
times at startup. And thanks to RCU the freeing was delayed.
Signed-off-by: Peter Lieven <p...@kamp.de>
The size of the node from the previous as->dispatch could be used as a
hint for the new one perhaps, avoiding the reallocation?
This here seems also to work:
diff --git a/exec.c b/exec.c
index 0122ef7..2691c0a 100644
--- a/exec.c
+++ b/exec.c
@@ -187,10 +187,12 @@ struct CPUAddressSpace {
static void phys_map_node_reserve(PhysPageMap *map, unsigned nodes)
{
+ static unsigned alloc_hint = 16;
if (map->nodes_nb + nodes > map->nodes_nb_alloc) {
- map->nodes_nb_alloc = MAX(map->nodes_nb_alloc * 2, 16);
+ map->nodes_nb_alloc = MAX(map->nodes_nb_alloc, alloc_hint);
map->nodes_nb_alloc = MAX(map->nodes_nb_alloc, map->nodes_nb + nodes);
map->nodes = g_renew(Node, map->nodes, map->nodes_nb_alloc);
+ alloc_hint = map->nodes_nb_alloc;
}
}
Question is still, mmap for this?
Peter
