The following commit has been merged into the sched/core branch of tip:
Commit-ID: 07bbecb3410617816a99e76a2df7576507a0c8ad
Gitweb: https://git.kernel.org/tip/07bbecb3410617816a99e76a2df7576507a0c8ad
Author: Alex Belits <abelits@xxxxxxxxxxx>
AuthorDate: Thu, 25 Jun 2020 18:34:43 -04:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 08 Jul 2020 11:39:02 +02:00
net: Restrict receive packets queuing to housekeeping CPUs
With the existing implementation of store_rps_map(), packets are queued
in the receive path on the backlog queues of other CPUs irrespective of
whether they are isolated or not. This could add a latency overhead to
any RT workload that is running on the same CPU.
Ensure that store_rps_map() only uses available housekeeping CPUs for
storing the rps_map.
Signed-off-by: Alex Belits <abelits@xxxxxxxxxxx>
Signed-off-by: Nitesh Narayan Lal <nitesh@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200625223443.2684-4-nitesh@xxxxxxxxxx
---
net/core/net-sysfs.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index e353b82..677868f 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -11,6 +11,7 @@
#include <linux/if_arp.h>
#include <linux/slab.h>
#include <linux/sched/signal.h>
+#include <linux/sched/isolation.h>
#include <linux/nsproxy.h>
#include <net/sock.h>
#include <net/net_namespace.h>
@@ -741,7 +742,7 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
{
struct rps_map *old_map, *map;
cpumask_var_t mask;
- int err, cpu, i;
+ int err, cpu, i, hk_flags;
static DEFINE_MUTEX(rps_map_mutex);
if (!capable(CAP_NET_ADMIN))
@@ -756,6 +757,13 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
return err;
}
+ hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
+ cpumask_and(mask, mask, housekeeping_cpumask(hk_flags));
+ if (cpumask_empty(mask)) {
+ free_cpumask_var(mask);
+ return -EINVAL;
+ }
+
map = kzalloc(max_t(unsigned int,
RPS_MAP_SIZE(cpumask_weight(mask)), L1_CACHE_BYTES),
GFP_KERNEL);
|