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Subject[PATCH 6/8] idr: avoid ping-pong
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The ida callers always calls ida_pre_get() before ida_get_new*().
ida_pre_get() will do layer allocation, and ida_get_new*() will do layer removal.

It causes an unneeded ping-pong. The speculative layer removal in
ida_get_new*() can't result expected optimization.

So we remove the unneeded layer removal in ida_get_new*().

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
lib/idr.c | 11 -----------
1 files changed, 0 insertions(+), 11 deletions(-)

diff --git a/lib/idr.c b/lib/idr.c
index e4f9965..be0b6ff 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -1001,17 +1001,6 @@ int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)

*p_id = id;

- /* Each leaf node can handle nearly a thousand slots and the
- * whole idea of ida is to have small memory foot print.
- * Throw away extra resources one by one after each successful
- * allocation.
- */
- if (ida->idr.id_free_cnt || ida->free_bitmap) {
- struct idr_layer *p = get_from_free_list(&ida->idr);
- if (p)
- kmem_cache_free(idr_layer_cache, p);
- }
-
return 0;
}
EXPORT_SYMBOL(ida_get_new_above);
--
1.7.4.4


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