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From: Nitesh Narayan Lal <nitesh@redhat.com>
To: linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
	frederic@kernel.org, mtosatti@redhat.com, juri.lelli@redhat.com,
	abelits@marvell.com, bhelgaas@google.com,
	linux-pci@vger.kernel.org, rostedt@goodmis.org, mingo@kernel.org,
	peterz@infradead.org, tglx@linutronix.de, davem@davemloft.net,
	akpm@linux-foundation.org, sfr@canb.auug.org.au,
	stephen@networkplumber.org, rppt@linux.vnet.ibm.com,
	jinyuqi@huawei.com, zhangshaokun@hisilicon.com
Subject: [Patch v4 3/3] net: Restrict receive packets queuing to housekeeping CPUs
Date: Thu, 25 Jun 2020 18:34:43 -0400
Message-ID: <20200625223443.2684-4-nitesh@redhat.com> (raw)
In-Reply-To: <20200625223443.2684-1-nitesh@redhat.com>

From: Alex Belits <abelits@marvell.com>

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>
---
 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 e353b822bb15..677868fea316 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);
-- 
2.18.4


  parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-25 22:34 [PATCH v4 0/3] Preventing job distribution to isolated CPUs Nitesh Narayan Lal
2020-06-25 22:34 ` [Patch v4 1/3] lib: Restrict cpumask_local_spread to houskeeping CPUs Nitesh Narayan Lal
2020-06-29 16:11   ` Nitesh Narayan Lal
2020-07-01  0:32     ` Andrew Morton
2020-07-01  0:47       ` Nitesh Narayan Lal
2020-06-25 22:34 ` [Patch v4 2/3] PCI: Restrict probe functions to housekeeping CPUs Nitesh Narayan Lal
2020-06-25 22:34 ` Nitesh Narayan Lal [this message]
2020-06-26 11:14   ` [Patch v4 3/3] net: Restrict receive packets queuing " Peter Zijlstra
2020-06-26 17:20     ` David Miller

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