| Message ID | 20180802171310.9295-1-jeffrey.t.kirsher@intel.com |
|---|---|
| State | Accepted |
| Delegated to: | Jeff Kirsher |
| Headers | show |
| Series | igb: reduce CPU0 latency when updating statistics | expand |
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@osuosl.org] On > Behalf Of Jeff Kirsher > Sent: Thursday, August 2, 2018 10:13 AM > To: intel-wired-lan@lists.osuosl.org > Cc: Jan Jablonsky <jan.jablonsky@thalesgroup.com>; Bernhard Kaindl > <bernhard.kaindl@thalesgroup.com> > Subject: [Intel-wired-lan] [PATCH] igb: reduce CPU0 latency when updating > statistics > > This change is based off of the work and suggestion of Jan Jablonsky > <jan.jablonsky@thalesgroup.com>. > > The Watchdog workqueue in igb driver is scheduled every 2s for each > network interface. That includes updating a statistics protected by > spinlock. Function igb_update_stats in this case will be protected > against preemption. According to number of a statistics registers > (cca 60), processing this function might cause additional cpu load > on CPU0. > > In case of statistics spinlock may be replaced with mutex, which > reduce latency on CPU0. > > CC: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com> > CC: Jan Jablonsky <jan.jablonsky@thalesgroup.com> > Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> > --- > drivers/net/ethernet/intel/igb/igb.h | 2 +- > drivers/net/ethernet/intel/igb/igb_ethtool.c | 4 ++-- > drivers/net/ethernet/intel/igb/igb_main.c | 14 +++++++------- > 3 files changed, 10 insertions(+), 10 deletions(-) Tested-by: Aaron Brown <aaron.f.brown@intel.com>
diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h index ca54e268d157..fe1592ae8769 100644 --- a/drivers/net/ethernet/intel/igb/igb.h +++ b/drivers/net/ethernet/intel/igb/igb.h @@ -515,7 +515,7 @@ struct igb_adapter { /* OS defined structs */ struct pci_dev *pdev; - spinlock_t stats64_lock; + struct mutex stats64_lock; struct rtnl_link_stats64 stats64; /* structs defined in e1000_hw.h */ diff --git a/drivers/net/ethernet/intel/igb/igb_ethtool.c b/drivers/net/ethernet/intel/igb/igb_ethtool.c index 5acf3b743876..e0a0e62b142a 100644 --- a/drivers/net/ethernet/intel/igb/igb_ethtool.c +++ b/drivers/net/ethernet/intel/igb/igb_ethtool.c @@ -2295,7 +2295,7 @@ static void igb_get_ethtool_stats(struct net_device *netdev, int i, j; char *p; - spin_lock(&adapter->stats64_lock); + mutex_lock(&adapter->stats64_lock); igb_update_stats(adapter); for (i = 0; i < IGB_GLOBAL_STATS_LEN; i++) { @@ -2338,7 +2338,7 @@ static void igb_get_ethtool_stats(struct net_device *netdev, } while (u64_stats_fetch_retry_irq(&ring->rx_syncp, start)); i += IGB_RX_QUEUE_STATS_LEN; } - spin_unlock(&adapter->stats64_lock); + mutex_unlock(&adapter->stats64_lock); } static void igb_get_strings(struct net_device *netdev, u32 stringset, u8 *data) diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index 1ed4f073e7e0..3cca19dade84 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -2209,9 +2209,9 @@ void igb_down(struct igb_adapter *adapter) del_timer_sync(&adapter->phy_info_timer); /* record the stats before reset*/ - spin_lock(&adapter->stats64_lock); + mutex_lock(&adapter->stats64_lock); igb_update_stats(adapter); - spin_unlock(&adapter->stats64_lock); + mutex_unlock(&adapter->stats64_lock); adapter->link_speed = 0; adapter->link_duplex = 0; @@ -3849,7 +3849,7 @@ static int igb_sw_init(struct igb_adapter *adapter) adapter->min_frame_size = ETH_ZLEN + ETH_FCS_LEN; spin_lock_init(&adapter->nfc_lock); - spin_lock_init(&adapter->stats64_lock); + mutex_init(&adapter->stats64_lock); #ifdef CONFIG_PCI_IOV switch (hw->mac.type) { case e1000_82576: @@ -5414,9 +5414,9 @@ static void igb_watchdog_task(struct work_struct *work) } } - spin_lock(&adapter->stats64_lock); + mutex_lock(&adapter->stats64_lock); igb_update_stats(adapter); - spin_unlock(&adapter->stats64_lock); + mutex_unlock(&adapter->stats64_lock); for (i = 0; i < adapter->num_tx_queues; i++) { struct igb_ring *tx_ring = adapter->tx_ring[i]; @@ -6242,10 +6242,10 @@ static void igb_get_stats64(struct net_device *netdev, { struct igb_adapter *adapter = netdev_priv(netdev); - spin_lock(&adapter->stats64_lock); + mutex_lock(&adapter->stats64_lock); igb_update_stats(adapter); memcpy(stats, &adapter->stats64, sizeof(*stats)); - spin_unlock(&adapter->stats64_lock); + mutex_unlock(&adapter->stats64_lock); } /**
This change is based off of the work and suggestion of Jan Jablonsky <jan.jablonsky@thalesgroup.com>. The Watchdog workqueue in igb driver is scheduled every 2s for each network interface. That includes updating a statistics protected by spinlock. Function igb_update_stats in this case will be protected against preemption. According to number of a statistics registers (cca 60), processing this function might cause additional cpu load on CPU0. In case of statistics spinlock may be replaced with mutex, which reduce latency on CPU0. CC: Bernhard Kaindl <bernhard.kaindl@thalesgroup.com> CC: Jan Jablonsky <jan.jablonsky@thalesgroup.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> --- drivers/net/ethernet/intel/igb/igb.h | 2 +- drivers/net/ethernet/intel/igb/igb_ethtool.c | 4 ++-- drivers/net/ethernet/intel/igb/igb_main.c | 14 +++++++------- 3 files changed, 10 insertions(+), 10 deletions(-)