rds_page_remainder_alloc() obtains the current CPU with get_cpu() while
disabling preemption. Then the CPU number is used to access the per-CPU
data structure via per_cpu().
This can be optimized by relying on local_bh_disable() to provide a
stable CPU number/ avoid migration and then using this_cpu_ptr() to
retrieve the data structure.
Cc: Allison Henderson <allison.henderson@xxxxxxxxxx>
Cc: linux-rdma@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
net/rds/page.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/net/rds/page.c b/net/rds/page.c
index e0dd4f62ea47a..58a8548a915a9 100644
--- a/net/rds/page.c
+++ b/net/rds/page.c
@@ -86,8 +86,8 @@ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
goto out;
}
- rem = &per_cpu(rds_page_remainders, get_cpu());
local_bh_disable();
+ rem = this_cpu_ptr(&rds_page_remainders);
while (1) {
/* avoid a tiny region getting stuck by tossing it */
@@ -116,12 +116,11 @@ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
/* alloc if there is nothing for us to use */
local_bh_enable();
- put_cpu();
page = alloc_page(gfp);
- rem = &per_cpu(rds_page_remainders, get_cpu());
local_bh_disable();
+ rem = this_cpu_ptr(&rds_page_remainders);
if (!page) {
ret = -ENOMEM;
@@ -140,7 +139,6 @@ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
}
local_bh_enable();
- put_cpu();
out:
rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
--
2.47.2
