Hi, David The code to be removed set the minimum interrupt interval of queue 0 to 0x79E. According to datasheet, this value has something wrong because it wirte the least reserved 3 bits to 110. Anyway, it intends to set a non-zero minimum interrupt interval.
ixgbe_configure_msix( ) is only called by ixgbe_dev_start( ). After it is called, ixgbe_dev_rx_ini( ) is called. And ixgbe_set_rsc( ) is called in ixgbe_dev_rx_init( ). In ixgbe_set_rsc( ), if RSC is enabled, the ITR (interrupt interval) is set to 500us again. So I think enabling immediate interrupt response by removing these codes is not suitable. It should be done in other code where interrupt mode Rx is configured. > Subject: [dpdk-dev] [PATCH] net/ixgbe: keep interrupt throttling disabled > > The code being removed would enable time-based interrupt throttling for the > first MSI-X interrupt vector. This would throttle link status change > interrupts > for NICs bound to vfio_pci driver; but for igb_uio driver, rx queue 0 > interrupts > would be throttled. This resulted in inconsistent latencies in a DPDK > interrupt > mode packet forwarding application between the 2 drivers. > > We'd like DPDK interrupt mode applications to be awaken by inbound packet > interrupts as soon as they are received regardless of interrupt interval, > interrupt throttling should be kept disabled. > > Signed-off-by: David Su <david.w...@intel.com> > --- > drivers/net/ixgbe/ixgbe_ethdev.c | 2 -- > 1 files changed, 0 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c > b/drivers/net/ixgbe/ixgbe_ethdev.c > index bdf4e2b..fdfb7a6 100644 > --- a/drivers/net/ixgbe/ixgbe_ethdev.c > +++ b/drivers/net/ixgbe/ixgbe_ethdev.c > @@ -5815,8 +5815,6 @@ ixgbe_configure_msix(struct rte_eth_dev *dev) > default: > break; > } > - IXGBE_WRITE_REG(hw, IXGBE_EITR(IXGBE_MISC_VEC_ID), > - IXGBE_MIN_INTER_INTERRUPT_INTERVAL_DEFAULT & 0xFFF); > > /* set up to autoclear timer, and the vectors */ > mask = IXGBE_EIMS_ENABLE_MASK; > -- > 1.7.0.4
