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authorBen Hutchings <bhutchings@solarflare.com>2011-01-19 11:03:53 +0000
committerDavid S. Miller <davem@davemloft.net>2011-01-24 14:53:01 -0800
commitc445477d74ab3779d1386ab797fbb9b628eb9f64 (patch)
tree3ee70b7748c6c63a688f367e5ffd83fde21b87e3 /net
parentc39649c331c70952700f99832b03f87e9d7f5b4b (diff)
net: RPS: Enable hardware acceleration of RFS
Allow drivers for multiqueue hardware with flow filter tables to accelerate RFS. The driver must: 1. Set net_device::rx_cpu_rmap to a cpu_rmap of the RX completion IRQs (in queue order). This will provide a mapping from CPUs to the queues for which completions are handled nearest to them. 2. Implement net_device_ops::ndo_rx_flow_steer. This operation adds or replaces a filter steering the given flow to the given RX queue, if possible. 3. Periodically remove filters for which rps_may_expire_flow() returns true. Signed-off-by: Ben Hutchings <bhutchings@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/Kconfig6
-rw-r--r--net/core/dev.c97
2 files changed, 97 insertions, 6 deletions
diff --git a/net/Kconfig b/net/Kconfig
index 72840626284b..79cabf1ee68b 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -221,6 +221,12 @@ config RPS
depends on SMP && SYSFS && USE_GENERIC_SMP_HELPERS
default y
+config RFS_ACCEL
+ boolean
+ depends on RPS && GENERIC_HARDIRQS
+ select CPU_RMAP
+ default y
+
config XPS
boolean
depends on SMP && SYSFS && USE_GENERIC_SMP_HELPERS
diff --git a/net/core/dev.c b/net/core/dev.c
index d162ba8d622d..aa761472f9e2 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -132,6 +132,7 @@
#include <trace/events/skb.h>
#include <linux/pci.h>
#include <linux/inetdevice.h>
+#include <linux/cpu_rmap.h>
#include "net-sysfs.h"
@@ -2588,6 +2589,53 @@ EXPORT_SYMBOL(__skb_get_rxhash);
struct rps_sock_flow_table __rcu *rps_sock_flow_table __read_mostly;
EXPORT_SYMBOL(rps_sock_flow_table);
+static struct rps_dev_flow *
+set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
+ struct rps_dev_flow *rflow, u16 next_cpu)
+{
+ u16 tcpu;
+
+ tcpu = rflow->cpu = next_cpu;
+ if (tcpu != RPS_NO_CPU) {
+#ifdef CONFIG_RFS_ACCEL
+ struct netdev_rx_queue *rxqueue;
+ struct rps_dev_flow_table *flow_table;
+ struct rps_dev_flow *old_rflow;
+ u32 flow_id;
+ u16 rxq_index;
+ int rc;
+
+ /* Should we steer this flow to a different hardware queue? */
+ if (!skb_rx_queue_recorded(skb) || !dev->rx_cpu_rmap)
+ goto out;
+ rxq_index = cpu_rmap_lookup_index(dev->rx_cpu_rmap, next_cpu);
+ if (rxq_index == skb_get_rx_queue(skb))
+ goto out;
+
+ rxqueue = dev->_rx + rxq_index;
+ flow_table = rcu_dereference(rxqueue->rps_flow_table);
+ if (!flow_table)
+ goto out;
+ flow_id = skb->rxhash & flow_table->mask;
+ rc = dev->netdev_ops->ndo_rx_flow_steer(dev, skb,
+ rxq_index, flow_id);
+ if (rc < 0)
+ goto out;
+ old_rflow = rflow;
+ rflow = &flow_table->flows[flow_id];
+ rflow->cpu = next_cpu;
+ rflow->filter = rc;
+ if (old_rflow->filter == rflow->filter)
+ old_rflow->filter = RPS_NO_FILTER;
+ out:
+#endif
+ rflow->last_qtail =
+ per_cpu(softnet_data, tcpu).input_queue_head;
+ }
+
+ return rflow;
+}
+
/*
* get_rps_cpu is called from netif_receive_skb and returns the target
* CPU from the RPS map of the receiving queue for a given skb.
@@ -2658,12 +2706,9 @@ static int get_rps_cpu(struct net_device *dev, struct sk_buff *skb,
if (unlikely(tcpu != next_cpu) &&
(tcpu == RPS_NO_CPU || !cpu_online(tcpu) ||
((int)(per_cpu(softnet_data, tcpu).input_queue_head -
- rflow->last_qtail)) >= 0)) {
- tcpu = rflow->cpu = next_cpu;
- if (tcpu != RPS_NO_CPU)
- rflow->last_qtail = per_cpu(softnet_data,
- tcpu).input_queue_head;
- }
+ rflow->last_qtail)) >= 0))
+ rflow = set_rps_cpu(dev, skb, rflow, next_cpu);
+
if (tcpu != RPS_NO_CPU && cpu_online(tcpu)) {
*rflowp = rflow;
cpu = tcpu;
@@ -2684,6 +2729,46 @@ done:
return cpu;
}
+#ifdef CONFIG_RFS_ACCEL
+
+/**
+ * rps_may_expire_flow - check whether an RFS hardware filter may be removed
+ * @dev: Device on which the filter was set
+ * @rxq_index: RX queue index
+ * @flow_id: Flow ID passed to ndo_rx_flow_steer()
+ * @filter_id: Filter ID returned by ndo_rx_flow_steer()
+ *
+ * Drivers that implement ndo_rx_flow_steer() should periodically call
+ * this function for each installed filter and remove the filters for
+ * which it returns %true.
+ */
+bool rps_may_expire_flow(struct net_device *dev, u16 rxq_index,
+ u32 flow_id, u16 filter_id)
+{
+ struct netdev_rx_queue *rxqueue = dev->_rx + rxq_index;
+ struct rps_dev_flow_table *flow_table;
+ struct rps_dev_flow *rflow;
+ bool expire = true;
+ int cpu;
+
+ rcu_read_lock();
+ flow_table = rcu_dereference(rxqueue->rps_flow_table);
+ if (flow_table && flow_id <= flow_table->mask) {
+ rflow = &flow_table->flows[flow_id];
+ cpu = ACCESS_ONCE(rflow->cpu);
+ if (rflow->filter == filter_id && cpu != RPS_NO_CPU &&
+ ((int)(per_cpu(softnet_data, cpu).input_queue_head -
+ rflow->last_qtail) <
+ (int)(10 * flow_table->mask)))
+ expire = false;
+ }
+ rcu_read_unlock();
+ return expire;
+}
+EXPORT_SYMBOL(rps_may_expire_flow);
+
+#endif /* CONFIG_RFS_ACCEL */
+
/* Called from hardirq (IPI) context */
static void rps_trigger_softirq(void *data)
{