[PATCH RFC: linux-next 2/2] ixgbe: Example usage of the new IRQ affinity_hint callback

Peter P Waskiewicz Jr
2010-04-19T04:58:09Z

This patch uses the new IRQ affinity_hint callback mechanism.
It serves purely as an example of how a low-level driver can
utilize this new interface.

An official ixgbe patch will be pushed through netdev once the
IRQ patches have been accepted and merged.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
---

drivers/net/ixgbe/ixgbe.h | 2 ++
drivers/net/ixgbe/ixgbe_main.c | 51 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 52 insertions(+), 1 deletions(-)

diff --git a/drivers/net/ixgbe/ixgbe.h b/drivers/net/ixgbe/ixgbe.h
index 79c35ae..c220b9f 100644
--- a/drivers/net/ixgbe/ixgbe.h
+++ b/drivers/net/ixgbe/ixgbe.h
@@ -32,6 +32,7 @@
#include <linux/pci.h>
#include <linux/netdevice.h>
#include <linux/aer.h>
+#include <linux/cpumask.h>

#include "ixgbe_type.h"
#include "ixgbe_common.h"
@@ -236,6 +237,7 @@ struct ixgbe_q_vector {
u8 tx_itr;
u8 rx_itr;
u32 eitr;
+ cpumask_var_t affinity_mask;
};

/* Helper macros to switch between ints/sec and what the register uses.
diff --git a/drivers/net/ixgbe/ixgbe_main.c b/drivers/net/ixgbe/ixgbe_main.c
index 1b1419c..3e00d41 100644
--- a/drivers/net/ixgbe/ixgbe_main.c
+++ b/drivers/net/ixgbe/ixgbe_main.c
@@ -1031,6 +1031,36 @@ next_desc:
return cleaned;
}

+static unsigned int ixgbe_irq_affinity_callback(cpumask_var_t mask,
+ unsigned int irq, void *dev)
+{
+ struct ixgbe_adapter *adapter = (struct ixgbe_adapter *)dev;
+ int i, q_vectors = adapter->num_msix_vectors - NON_Q_VECTORS;
+
+ if (test_bit(__IXGBE_DOWN, &adapter->state))
+ return -EINVAL;
+
+ /*
+ * Loop through the msix_entries array, looking for the vector that
+ * matches the irq passed to us. Once we find it, use that index to
+ * grab the corresponding q_vector (1 to 1 mapping), and grab the
+ * cpumask from that q_vector.
+ */
+ for (i = 0; i < q_vectors; i++)
+ if (adapter->msix_entries[i].vector == irq)
+ break;
+
+ if (i == q_vectors)
+ return -EINVAL;
+
+ if (adapter->q_vector[i]->affinity_mask)
+ cpumask_copy(mask, adapter->q_vector[i]->affinity_mask);
+ else
+ return -EINVAL;
+
+ return 0;
+}
+
static int ixgbe_clean_rxonly(struct napi_struct *, int);
/**
* ixgbe_configure_msix - Configure MSI-X hardware
@@ -1083,6 +1113,16 @@ static void ixgbe_configure_msix(struct ixgbe_adapter *adapter)
q_vector->eitr = adapter->rx_eitr_param;

ixgbe_write_eitr(q_vector);
+
+ /*
+ * Allocate the affinity_hint cpumask, assign the mask for
+ * this vector, and register our affinity_hint callback.
+ */
+ alloc_cpumask_var(&q_vector->affinity_mask, GFP_KERNEL);
+ cpumask_set_cpu(v_idx, q_vector->affinity_mask);
+ irq_register_affinity_hint(adapter->msix_entries[v_idx].vector,
+ adapter,
+ &ixgbe_irq_affinity_callback);
}

if (adapter->hw.mac.type == ixgbe_mac_82598EB)
@@ -3218,7 +3258,7 @@ void ixgbe_down(struct ixgbe_adapter *adapter)
struct ixgbe_hw *hw = &adapter->hw;
u32 rxctrl;
u32 txdctl;
- int i, j;
+ int i, j, num_q_vectors = adapter->num_msix_vectors - NON_Q_VECTORS;

/* signal that we are down to the interrupt handler */
set_bit(__IXGBE_DOWN, &adapter->state);
@@ -3251,6 +3291,14 @@ void ixgbe_down(struct ixgbe_adapter *adapter)

ixgbe_napi_disable_all(adapter);

+ for (i = 0; i < num_q_vectors; i++) {
+ struct ixgbe_q_vector *q_vector = adapter->q_vector[i];
+ /* unregister the affinity_hint callback */
+ irq_unregister_affinity_hint(adapter->msix_entries[i].vector);
+ /* release the CPU mask memory */
+ free_cpumask_var(q_vector->affinity_mask);
+ }
+
clear_bit(__IXGBE_SFP_MODULE_NOT_FOUND, &adapter->state);
del_timer_sync(&adapter->sfp_timer);
del_timer_sync(&adapter->watchdog_timer);
@@ -4052,6 +4100,7 @@ static void ixgbe_free_q_vectors(struct ixgbe_adapter *adapter)
struct ixgbe_q_vector *q_vector = adapter->q_vector[q_idx];
adapter->q_vector[q_idx] = NULL;
netif_napi_del(&q_vector->napi);
+ free_cpumask_var(q_vector->affinity_mask);
kfree(q_vector);
}
}