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Date: Mon, 8 Aug 2022 11:56:01 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
To: linux-mm@...ck.org, akpm@...ux-foundation.org
Cc: Wei Xu <weixugc@...gle.com>, Huang Ying <ying.huang@...el.com>,
Yang Shi <shy828301@...il.com>,
Davidlohr Bueso <dave@...olabs.net>,
Tim C Chen <tim.c.chen@...el.com>,
Michal Hocko <mhocko@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Hesham Almatary <hesham.almatary@...wei.com>,
Dave Hansen <dave.hansen@...el.com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Alistair Popple <apopple@...dia.com>,
Dan Williams <dan.j.williams@...el.com>,
Johannes Weiner <hannes@...xchg.org>, jvgediya.oss@...il.com,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
Subject: [PATCH v13 9/9] lib/nodemask: Optimize node_random for nodemask with single NUMA node
The most common case for certain node_random usage (demotion nodemask) is with
nodemask weight 1. We can avoid calling get_random_init() in that case and
always return the only node set in the nodemask.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.ibm.com>
---
lib/nodemask.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/lib/nodemask.c b/lib/nodemask.c
index e22647f5181b..c91a6b0404a5 100644
--- a/lib/nodemask.c
+++ b/lib/nodemask.c
@@ -20,12 +20,21 @@ EXPORT_SYMBOL(__next_node_in);
*/
int node_random(const nodemask_t *maskp)
{
- int w, bit = NUMA_NO_NODE;
+ int w, bit;
w = nodes_weight(*maskp);
- if (w)
+ switch (w) {
+ case 0:
+ bit = NUMA_NO_NODE;
+ break;
+ case 1:
+ bit = __first_node(maskp);
+ break;
+ default:
bit = bitmap_ord_to_pos(maskp->bits,
- get_random_int() % w, MAX_NUMNODES);
+ get_random_int() % w, MAX_NUMNODES);
+ break;
+ }
return bit;
}
#endif
--
2.37.1
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