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Message-ID: <BL0PR11MB31228261472A683DF589C61EBD639@BL0PR11MB3122.namprd11.prod.outlook.com>
Date: Thu, 20 Apr 2023 16:39:52 +0000
From: "Pucha, HimasekharX Reddy" <himasekharx.reddy.pucha@...el.com>
To: Joe Damato <jdamato@...tly.com>,
"intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
"kuba@...nel.org" <kuba@...nel.org>
Subject: RE: [Intel-wired-lan] [PATCH net v2 2/2] ixgbe: Enable setting RSS
table to default values
> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf Of Joe Damato
> Sent: Monday, April 17, 2023 10:29 AM
> To: intel-wired-lan@...ts.osuosl.org
> Cc: netdev@...r.kernel.org; Nguyen, Anthony L <anthony.l.nguyen@...el.com>; Brandeburg, Jesse <jesse.brandeburg@...el.com>; kuba@...nel.org
> Subject: Re: [Intel-wired-lan] [PATCH net v2 2/2] ixgbe: Enable setting RSS table to default values
>
> On Sun, Apr 16, 2023 at 07:12:23PM +0000, Joe Damato wrote:
> ethtool uses `ETHTOOL_GRXRINGS` to compute how many queues are
> supported by RSS. The driver should return the smaller of either:
> - The maximum number of RSS queues the device supports, OR
> - The number of RX queues configured
>
> Prior to this change, running `ethtool -X $iface default` fails if the
> number of queues configured is larger than the number supported by
> RSS, even though changing the queue count correctly resets the
> flowhash to use all supported queues.
>
> Other drivers (for example, i40e) will succeed but the flow hash will
> reset to support the maximum number of queues supported by RSS, even
> if that amount is smaller than the configured amount.
>
> Prior to this change:
>
> $ sudo ethtool -L eth1 combined 20
> $ sudo ethtool -x eth1
> RX flow hash indirection table for eth1 with 20 RX ring(s):
> 0: 0 1 2 3 4 5 6 7
> 8: 8 9 10 11 12 13 14 15
> 16: 0 1 2 3 4 5 6 7
> 24: 8 9 10 11 12 13 14 15
> 32: 0 1 2 3 4 5 6 7
> ...
>
> You can see that the flowhash was correctly set to use the maximum
> number of queues supported by the driver (16).
>
> However, asking the NIC to reset to "default" fails:
>
> $ sudo ethtool -X eth1 default
> Cannot set RX flow hash configuration: Invalid argument
>
> After this change, the flowhash can be reset to default which will use
> all of the available RSS queues (16) or the configured queue count,
> whichever is smaller.
>
> Starting with eth1 which has 10 queues and a flowhash distributing to
> all 10 queues:
>
> $ sudo ethtool -x eth1
> RX flow hash indirection table for eth1 with 10 RX ring(s):
> 0: 0 1 2 3 4 5 6 7
> 8: 8 9 0 1 2 3 4 5
> 16: 6 7 8 9 0 1 2 3
> ...
>
> Increasing the queue count to 48 resets the flowhash to distribute to
> 16 queues, as it did before this patch:
>
> $ sudo ethtool -L eth1 combined 48
> $ sudo ethtool -x eth1
> RX flow hash indirection table for eth1 with 16 RX ring(s):
> 0: 0 1 2 3 4 5 6 7
> 8: 8 9 10 11 12 13 14 15
> 16: 0 1 2 3 4 5 6 7
> ...
>
> Due to the other bugfix in this series, the flowhash can be set to use
> queues 0-5:
>
> $ sudo ethtool -X eth1 equal 5
> $ sudo ethtool -x eth1
> RX flow hash indirection table for eth1 with 16 RX ring(s):
> 0: 0 1 2 3 4 0 1 2
> 8: 3 4 0 1 2 3 4 0
> 16: 1 2 3 4 0 1 2 3
> ...
>
> Due to this bugfix, the flowhash can be reset to default and use 16
> queues:
>
> $ sudo ethtool -X eth1 default
> $ sudo ethtool -x eth1
> RX flow hash indirection table for eth1 with 16 RX ring(s):
> 0: 0 1 2 3 4 5 6 7
> 8: 8 9 10 11 12 13 14 15
> 16: 0 1 2 3 4 5 6 7
> ...
>
> Fixes: 91cd94bfe4f0 ("ixgbe: add basic support for setting and getting nfc
controls")
>
> Signed-off-by: Joe Damato <jdamato@...tly.com>
> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@...el.com>
> ---
> .../net/ethernet/intel/ixgbe/ixgbe_ethtool.c | 19
> ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@...el.com> (A Contingent worker at Intel)
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