在 2023/6/1 10:16, Liam R. Howlett 写道:
Calculate the number of nodes based on the pending write action instead
of assuming the worst case.
This addresses a performance regression introduced in platforms that
have longer allocation timing.
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
---
lib/maple_tree.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 43 insertions(+), 1 deletion(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index adf662bc413e..5ea211c3f186 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5541,9 +5541,51 @@ EXPORT_SYMBOL_GPL(mas_store_prealloc);
*/
int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp)
{
+ MA_WR_STATE(wr_mas, mas, entry);
+ unsigned char node_size;
+ int request = 1;
If either mas_wr_append() or mas_wr_slot_store() succeeds,
or does a simple replacement, we don't need to make any allocations.
int ret;
- mas_node_count_gfp(mas, 1 + mas_mt_height(mas) * 3, gfp);
+
+ if (unlikely(!mas->index && mas->last == ULONG_MAX))
+ goto ask_now;
+
+ mas_wr_store_setup(&wr_mas);
+ wr_mas.content = mas_start(mas);
+ /* Root expand */
+ if (unlikely(mas_is_none(mas) || mas_is_ptr(mas)))
+ goto ask_now;
+
+ if (unlikely(!mas_wr_walk(&wr_mas))) {
+ /* Spanning store, use worst case for now */
+ request = 1 + mas_mt_height(mas) * 3;
+ goto ask_now;
+ }
+
+ /* At this point, we are at the leaf node that needs to be altered. */
+ /* Exact fit, no nodes needed. */
+ if (wr_mas.r_min == mas->index && wr_mas.r_max == mas->last)
+ return 0;
+
+ mas_wr_end_piv(&wr_mas);
+ node_size = mas_wr_new_end(&wr_mas);
+ if (node_size >= mt_slots[wr_mas.type]) {
+ /* Split, worst case for now. */
+ request = 1 + mas_mt_height(mas) * 2;
+ goto ask_now;
+ }
+
+ /* New root needs a singe node */
+ if (unlikely(mte_is_root(mas->node)))
+ goto ask_now;
+
+ /* Potential spanning rebalance collapsing a node, use worst-case */
+ if (node_size - 1 <= mt_min_slots[wr_mas.type])
+ request = mas_mt_height(mas) * 2 - 1;
+
+ /* node store, slot store needs one node */
+ask_now:
+ mas_node_count_gfp(mas, request, gfp);
mas->mas_flags |= MA_STATE_PREALLOC;
if (likely(!mas_is_err(mas)))
return 0;
