sfc: Add support for busy polling
This patch adds the sfc driver code for implementing busy polling.
It adds ndo_busy_poll method and locking between it and napi poll.
It also adds each napi to the napi_hash right after netif_napi_add().
Uses efx_start_eventq and efx_stop_eventq in the self tests.
Signed-off-by: Shradha Shah <sshah@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index 4b80c0b..4cebe9d 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -272,6 +272,9 @@
struct efx_nic *efx = channel->efx;
int spent;
+ if (!efx_channel_lock_napi(channel))
+ return budget;
+
netif_vdbg(efx, intr, efx->net_dev,
"channel %d NAPI poll executing on CPU %d\n",
channel->channel, raw_smp_processor_id());
@@ -311,6 +314,7 @@
efx_nic_eventq_read_ack(channel);
}
+ efx_channel_unlock_napi(channel);
return spent;
}
@@ -357,7 +361,7 @@
}
/* Enable event queue processing and NAPI */
-static void efx_start_eventq(struct efx_channel *channel)
+void efx_start_eventq(struct efx_channel *channel)
{
netif_dbg(channel->efx, ifup, channel->efx->net_dev,
"chan %d start event queue\n", channel->channel);
@@ -366,17 +370,20 @@
channel->enabled = true;
smp_wmb();
+ efx_channel_enable(channel);
napi_enable(&channel->napi_str);
efx_nic_eventq_read_ack(channel);
}
/* Disable event queue processing and NAPI */
-static void efx_stop_eventq(struct efx_channel *channel)
+void efx_stop_eventq(struct efx_channel *channel)
{
if (!channel->enabled)
return;
napi_disable(&channel->napi_str);
+ while (!efx_channel_disable(channel))
+ usleep_range(1000, 20000);
channel->enabled = false;
}
@@ -1960,6 +1967,8 @@
channel->napi_dev = efx->net_dev;
netif_napi_add(channel->napi_dev, &channel->napi_str,
efx_poll, napi_weight);
+ napi_hash_add(&channel->napi_str);
+ efx_channel_init_lock(channel);
}
static void efx_init_napi(struct efx_nic *efx)
@@ -1972,8 +1981,10 @@
static void efx_fini_napi_channel(struct efx_channel *channel)
{
- if (channel->napi_dev)
+ if (channel->napi_dev) {
netif_napi_del(&channel->napi_str);
+ napi_hash_del(&channel->napi_str);
+ }
channel->napi_dev = NULL;
}
@@ -2008,6 +2019,37 @@
#endif
+#ifdef CONFIG_NET_RX_BUSY_POLL
+static int efx_busy_poll(struct napi_struct *napi)
+{
+ struct efx_channel *channel =
+ container_of(napi, struct efx_channel, napi_str);
+ struct efx_nic *efx = channel->efx;
+ int budget = 4;
+ int old_rx_packets, rx_packets;
+
+ if (!netif_running(efx->net_dev))
+ return LL_FLUSH_FAILED;
+
+ if (!efx_channel_lock_poll(channel))
+ return LL_FLUSH_BUSY;
+
+ old_rx_packets = channel->rx_queue.rx_packets;
+ efx_process_channel(channel, budget);
+
+ rx_packets = channel->rx_queue.rx_packets - old_rx_packets;
+
+ /* There is no race condition with NAPI here.
+ * NAPI will automatically be rescheduled if it yielded during busy
+ * polling, because it was not able to take the lock and thus returned
+ * the full budget.
+ */
+ efx_channel_unlock_poll(channel);
+
+ return rx_packets;
+}
+#endif
+
/**************************************************************************
*
* Kernel net device interface
@@ -2177,6 +2219,9 @@
.ndo_poll_controller = efx_netpoll,
#endif
.ndo_setup_tc = efx_setup_tc,
+#ifdef CONFIG_NET_RX_BUSY_POLL
+ .ndo_busy_poll = efx_busy_poll,
+#endif
#ifdef CONFIG_RFS_ACCEL
.ndo_rx_flow_steer = efx_filter_rfs,
#endif
@@ -2197,6 +2242,9 @@
#ifdef CONFIG_NET_POLL_CONTROLLER
.ndo_poll_controller = efx_netpoll,
#endif
+#ifdef CONFIG_NET_RX_BUSY_POLL
+ .ndo_busy_poll = efx_busy_poll,
+#endif
#ifdef CONFIG_RFS_ACCEL
.ndo_rx_flow_steer = efx_filter_rfs,
#endif