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net: Restrict receive packets queuing to housekeeping CPUs

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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
This commit is contained in:
Alex Belits 2020-06-25 18:34:43 -04:00 committed by Peter Zijlstra
parent 69a18b1869
commit 07bbecb341
1 changed files with 9 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

10
net/core/net-sysfs.c
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@ -11,6 +11,7 @@
#include <linux/if_arp.h> #include <linux/if_arp.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/sched/signal.h> #include <linux/sched/signal.h>
#include <linux/sched/isolation.h>
#include <linux/nsproxy.h> #include <linux/nsproxy.h>
#include <net/sock.h> #include <net/sock.h>
#include <net/net_namespace.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; struct rps_map *old_map, *map;
cpumask_var_t mask; cpumask_var_t mask;
int err, cpu, i; int err, cpu, i, hk_flags;
static DEFINE_MUTEX(rps_map_mutex); static DEFINE_MUTEX(rps_map_mutex);
if (!capable(CAP_NET_ADMIN)) if (!capable(CAP_NET_ADMIN))
@ -756,6 +757,13 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue,
return err; 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, map = kzalloc(max_t(unsigned int,
RPS_MAP_SIZE(cpumask_weight(mask)), L1_CACHE_BYTES), RPS_MAP_SIZE(cpumask_weight(mask)), L1_CACHE_BYTES),
GFP_KERNEL); GFP_KERNEL);