[Intel-wired-lan] [next PATCH S76-V2 07/13] i40e/i40evf: avoid dynamic ITR updates when polling or low packet rate

Bowers, AndrewX andrewx.bowers at intel.com
Thu Jul 20 18:08:02 UTC 2017


> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces at osuosl.org] On
> Behalf Of Alice Michael
> Sent: Friday, July 14, 2017 6:10 AM
> To: Michael, Alice <alice.michael at intel.com>; intel-wired-
> lan at lists.osuosl.org
> Subject: [Intel-wired-lan] [next PATCH S76-V2 07/13] i40e/i40evf: avoid
> dynamic ITR updates when polling or low packet rate
> 
> From: Jacob Keller <jacob.e.keller at intel.com>
> 
> The dynamic ITR algorithm depends on a calculation of usecs which assumes
> that the interrupts have been firing constantly at the interrupt throttle rate.
> This is not guaranteed because we could have a low packet rate, or have
> been polling in software.
> 
> We'll estimate whether this is the case by using jiffies to determine if we've
> been too long. If the time difference of jiffies is larger we are guaranteed to
> have an incorrect calculation. If the time difference of jiffies is smaller we
> might have been polling some but the difference shouldn't affect the
> calculation too much.
> 
> This ensures that we don't get stuck in BULK latency during certain rare
> situations where we receive bursts of packets that force us into napi polling.
> 
> Signed-off-by: Jacob Keller <jacob.e.keller at intel.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_txrx.c   | 22 +++++++++++++++++-----
>  drivers/net/ethernet/intel/i40e/i40e_txrx.h   |  1 +
>  drivers/net/ethernet/intel/i40evf/i40e_txrx.c | 22 +++++++++++++++++----
> -  drivers/net/ethernet/intel/i40evf/i40e_txrx.h |  1 +
>  4 files changed, 36 insertions(+), 10 deletions(-)

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




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