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SubjectRe: Regression: Approximate 34% performance hit in receive throughput over ixgbe seen due to build_skb patch
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> On May 22, 2018, at 12:23 PM, Alexander Duyck <alexander.duyck@gmail.com> wrote:
>
> 3. There should be a private flag that can be updated via "ethtool
> --set-priv-flags" called "legacy-rx" that you can enable that will
> roll back to the original that did the copy-break type approach for
> small packets and the headers of the frame.

With legacy-rx enabled, most of the regression goes away, but it's still present
as compared to the code without the patch; the regression then drops to about 6%:

# ethtool --show-priv-flags eno1
Private flags for eno1:
legacy-rx: on

Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec

65536 64 60.00 35934709 0 306.64
65536 60.00 33791739 288.35

Socket Message Elapsed Messages
Size Size Time Okay Errors Throughput
bytes bytes secs # # 10^6bits/sec

65536 64 60.00 39254351 0 334.97
65536 60.00 36761069 313.69

Is this variance to be expected, or do you think modification of the
interrupt delay would achieve better results?


William Kucharski

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