[Intel-wired-lan] [net-next v2 2/2] ethernet/intel: consolidate napi and napi exit

[Bowers, AndrewX]

> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces at osuosl.org] On
> Behalf Of Jeff Kirsher
> Sent: Thursday, November 8, 2018 2:56 PM
> To: intel-wired-lan at lists.osuosl.org
> Subject: [Intel-wired-lan] [net-next v2 2/2] ethernet/intel: consolidate napi
> and napi exit
> 
> From: Jesse Brandeburg <jesse.brandeburg at intel.com>
> 
> While reviewing code, I noticed that Eric Dumazet recommends that drivers
> check the return code of napi_complete_done, and use that to decide to
> enable interrupts or not when exiting poll.  One of the Intel drivers was
> already fixed (ixgbe).
> 
> Upon looking at the Intel drivers as a whole, we are handling our polling and
> napi exit in a few different ways based on whether we have multiqueue and
> whether we have tx cleanup included. Several drivers had the bug of exiting
> napi with return 0, which appears to mess up the accounting in the stack.
> 
> Consolidate all the napi routines to do best known way of exiting and to just
> mostly look like each other.
> 1) check return code of napi_complete_done to control interrupt enable
> 2) return the actual amount of work done.
> 3) return budget immediately if need napi poll again
> 
> Tested the changes on e1000e with a high interrupt rate set, and it shows
> about an 8% reduction in the CPU utilization when busy polling because we
> aren't re-enabling interrupts when we're about to be polled.
> 
> Signed-off-by: Jesse Brandeburg <jesse.brandeburg at intel.com>
> ---
> v2: fixed conflicts when applied to my next-queue tree, dev-queue
>     branch.  Most notably the hunk toward the ice driver did not apply
>     due to upstream driver changes already applied to my tree
> 
>  drivers/net/ethernet/intel/e100.c             | 10 +++++----
>  drivers/net/ethernet/intel/e1000/e1000_main.c | 11 +++++-----
>  drivers/net/ethernet/intel/e1000e/netdev.c    | 17 +++++++-------
>  drivers/net/ethernet/intel/fm10k/fm10k_main.c | 10 ++++-----
>  drivers/net/ethernet/intel/i40e/i40e_txrx.c   |  9 ++++----
>  drivers/net/ethernet/intel/iavf/iavf_txrx.c   |  9 ++++----
>  drivers/net/ethernet/intel/ice/ice_txrx.c     | 10 +++++----
>  drivers/net/ethernet/intel/igb/igb_main.c     | 10 +++++----
>  drivers/net/ethernet/intel/igbvf/netdev.c     |  9 +++++---
>  drivers/net/ethernet/intel/igc/igc_main.c     | 10 +++++----
>  .../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 22 +++++++++++--------
>  11 files changed, 73 insertions(+), 54 deletions(-)

Tested-by: Andrew Bowers <andrewx.bowers at intel.com>