net: Restrict receive packets queuing to housekeeping CPUs (07bbecb3) · Commits · 戴 / test

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@marvell.com> Signed-off-by:

Nitesh Narayan Lal <nitesh@redhat.com> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200625223443.2684-4-nitesh@redhat.com

net/core/net-sysfs.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -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);

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