From: Stephen Hemminger <stephen@networkplumber.org>
To: Nagesh Mallappa <mallappanagesh@gmail.com>
Cc: dev@dpdk.org
Subject: Re: RSS Hash value returned by the gvnic pmd dpdk driver not matching Toeplitz
Date: Wed, 15 May 2024 08:04:34 -0700 [thread overview]
Message-ID: <20240515080434.33abfd44@hermes.local> (raw)
In-Reply-To: <CABH5nGYTEJweZrockVxuU2YLgjjVi3QTL_0T__jyotxRt5mpSA@mail.gmail.com>
On Wed, 15 May 2024 13:50:38 +0530
Nagesh Mallappa <mallappanagesh@gmail.com> wrote:
> Hi Team,
>
> We are using a C3 GCP instance having GVNIC with DPDK enabled.
> We are using latest version of DPDK ( dpdk-24.03 ) to configure RSS key, we
> understand C3 GCP instance with gvnic supports Toeplitz rss algorithm (
> Reference -
> https://github.com/google/compute-virtual-ethernet-dpdk/blob/main/gve_ethdev.c
> ),
> but we are hitting below issue.
>
> *Problem Statement - The RSS Hash value returned by the gvnic driver is
> different and is not matching the one computed by Toeplitz.*
>
> Using below script to compute rss hash value from Toeplitz.
> (https://gist.github.com/joongh/16867705b03b49e393cbf91da3cb42a7)
>
> Consider below data to compute RSS Hash value -
>
> Source IP - 79.124.62.122
> Destination IP - 192.168.7.28
> Source Port - 49442
> Destination Port - 55327
> RSS Key - {0x94e3e97e, 0x4abac401, 0x1e0edbf, 0xe059e1f4, 0xb6e27dff,
> 0xdf55c916, 0xe9e6e4db, 0x1f9fb82c, 0x1e0edbf, 0xe059e1f4}
>
> *Hash Value returned by Toeplitz - 0x8bbafd0f*
>
> Gvnic dpdk pmd driver which uses Toeplitz RSS hash algorithm too is
> expected to compute above RSS Hash value but we see the Hash value stored
> in dpdk mbuf to be 0xc6a15941 which is not right.
> From the DPDK side we have ensured RSS offloading configuration is done
> appropriately, but still we are seeing above mismatch.
>
> We request you to please help us understand why this mismatch is happening
> and is this expected behavior of gvnic on C3 instance.
Could you see if it is a driver byte order issue by byteswapping the key?
next prev parent reply other threads:[~2024-05-15 15:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-15 8:20 Nagesh Mallappa
2024-05-15 15:04 ` Stephen Hemminger [this message]
2024-05-15 15:49 ` Nagesh Mallappa
2024-05-15 22:57 ` Stephen Hemminger
2024-05-16 8:18 ` Nagesh Mallappa
2024-05-16 8:56 ` Ferruh Yigit
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