netdev - Re: [PATCH V7 net-next 02/11] net/mlx5: Implement cqe_compress

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Message-ID: <d4ee68d6-7f57-4b24-970f-41a944a22481@gmail.com>
Date: Fri, 17 Oct 2025 17:54:57 -0400
From: Daniel Zahka <daniel.zahka@...il.com>
To: Saeed Mahameed <saeed@...nel.org>, "David S. Miller"
 <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>
Cc: Saeed Mahameed <saeedm@...dia.com>, netdev@...r.kernel.org,
 Tariq Toukan <tariqt@...dia.com>, Gal Pressman <gal@...dia.com>,
 Leon Romanovsky <leonro@...dia.com>, Jiri Pirko <jiri@...dia.com>,
 Jacob Keller <jacob.e.keller@...el.com>, Simon Horman <horms@...nel.org>
Subject: Re: [PATCH V7 net-next 02/11] net/mlx5: Implement cqe_compress_type
 via devlink params



On 10/17/25 5:51 PM, Daniel Zahka wrote:
>
>
> On 9/6/25 9:29 PM, Saeed Mahameed wrote:
>> From: Saeed Mahameed <saeedm@...dia.com>
>>
>> Selects which algorithm should be used by the NIC in order to decide 
>> rate of
>> CQE compression dependeng on PCIe bus conditions.
>>
>> Supported values:
>>
>> 1) balanced, merges fewer CQEs, resulting in a moderate compression 
>> ratio
>>     but maintaining a balance between bandwidth savings and performance
>> 2) aggressive, merges more CQEs into a single entry, achieving a higher
>>     compression rate and maximizing performance, particularly under high
>>     traffic loads.
>>
>
> Hello,
>
> I'm facing some issues when trying to use the devlink param introduced 
> in this patch. I have a multihost system with two hosts per CX7.
>
> My NIC is:
> $ lshw -C net
>   *-network
>        description: Ethernet interface
>        product: MT2910 Family [ConnectX-7]
>        vendor: Mellanox Technologies
>
> My fw version is: 28.43.1014
>
> To reproduce the problem I simply read the current cqe_compress_type 
> setting and then change it:
>
> $ devlink dev param show pci/0000:56:00.0 name cqe_compress_type
> pci/0000:56:00.0:
>   name cqe_compress_type type driver-specific
>     values:
>       cmode permanent value balanced
>
> $ devlink dev param set pci/0000:56:00.0 name cqe_compress_type value 
> "aggressive" cmode permanent
> kernel answers: Connection timed out
>
> from dmesg:
> [  257.111349] mlx5_core 0000:56:00.0: 
> wait_func_handle_exec_timeout:1159:(pid 72061): cmd[0]: 
> ACCESS_REG(0x805) No done completion
> [  257.137072] mlx5_core 0000:56:00.0: wait_func:1189:(pid 72061): 
> ACCESS_REG(0x805) timeout. Will cause a leak of a command resource
> [  270.871521] mlx5_core 0000:56:00.0: mlx5_cmd_comp_handler:1709:(pid 
> 0): Command completion arrived after timeout (entry idx = 0).
>
>
> subsequent attempts to use mstfwreset hang:
>
> $ ./mstfwreset -y -d 56:00.0 reset
> -E- Failed to send Register MFRL: Timed out trying to take the ICMD 
> semaphore (520).
>
> I can toggle the parameter ok using the mstconfig binary built from 
> the mstflint github repo.
>
> Let me know if I can provide any more information.
>
> Daniel

Sorry, I should have mentioned my kernel version. It is a vanilla 
net-next kernel from:
1c51450f1aff ("tcp: better handle TCP_TX_DELAY on established flows")