[Intel-wired-lan] [PATCH] fm10k: Update ITR scaling mechanism based on PCIe link speed

[Jeff Kirsher]

On Wed, 2015-04-29 at 17:10 -0700, Jacob Keller wrote:
> Red Rock Canyon's interrupt throttle timers are based on the PCIe link
> speed. Because of this, the value being programmed into the ITR
> registers must be scaled.
> 
> For the PF, this is as simple as reading the PCIe link speed and
> storing
> the result. However, in the case of SR-IOV, the VF's interrupt
> throttle
> timers are based on the link speed of the PF. However, the VF is
> unable
> to get the link speed information from its configuration space, so the
> PF must inform it of what scale to use.
> 
> Rather than pass this scale via mailbox message, take advantage of
> unused bits in the TDLEN register to pass the scale. It is the
> responsibility of the PF to program this for the VF while setting up
> the
> VF queues and the responsibility of the VF to get the information
> accordingly. This is preferable because it allows the VF to set up the
> interrupts properly during initialization and matches how the MAC
> address is passed in the TDBAL/TDBAH registers.
> 
> These changes also resolve an issue with the existing ITR scale being
> too restrictive. It would throttle down to 1300ints/s at 1538 byte
> frames. This patch modifies the algorithm to allow for a higher range
> of
> interrupts per second, from roughly 25000int/s up to 100000int/s
> depending on our detection of the workload.
> 
> This patch fixes a single receiving TCP_STREAM in netperf:
> - Before: 450 Mbps
> - After: 20,000 Mbps
> 
> Signed-off-by: Jacob Keller <jacob.e.keller at intel.com>
> Discovered-by: Matthew Vick <matthew.vick at intel.com>
> ---
>  drivers/net/ethernet/intel/fm10k/fm10k.h      |  4 ++++
>  drivers/net/ethernet/intel/fm10k/fm10k_main.c | 17 +++++++++++++----
>  drivers/net/ethernet/intel/fm10k/fm10k_pci.c  | 12 ++++++++++--
>  drivers/net/ethernet/intel/fm10k/fm10k_pf.c   | 18 +++++++++++++++++-
>  drivers/net/ethernet/intel/fm10k/fm10k_type.h |  9 +++++++++
>  drivers/net/ethernet/intel/fm10k/fm10k_vf.c   | 15 +++++++++++++--
>  6 files changed, 66 insertions(+), 9 deletions(-)

Dropping patch and await v2
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: This is a digitally signed message part
URL: <http://lists.osuosl.org/pipermail/intel-wired-lan/attachments/20150430/00c6c768/attachment.asc>