netdev - Re: [PATCH net-next v2] net/smc: add sysctl for smc_limit

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Message-ID: <905874a4-c000-4845-8fac-3fc4b79f43fd@linux.alibaba.com>
Date: Mon, 26 Aug 2024 11:02:14 +0800
From: "D. Wythe" <alibuda@...ux.alibaba.com>
To: Jan Karcher <jaka@...ux.ibm.com>, kgraul@...ux.ibm.com,
 wenjia@...ux.ibm.com, wintera@...ux.ibm.com, guwen@...ux.alibaba.com
Cc: kuba@...nel.org, davem@...emloft.net, netdev@...r.kernel.org,
 linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org,
 tonylu@...ux.alibaba.com, pabeni@...hat.com, edumazet@...gle.com
Subject: Re: [PATCH net-next v2] net/smc: add sysctl for smc_limit_hs



On 8/21/24 4:03 PM, Jan Karcher wrote:
>
>
> On 21/08/2024 04:36, D. Wythe wrote:
>> From: "D. Wythe" <alibuda@...ux.alibaba.com>
>>
>> In commit 48b6190a0042 ("net/smc: Limit SMC visits when handshake 
>> workqueue congested"),
>> we introduce a mechanism to put constraint on SMC connections visit
>> according to the pressure of SMC handshake process.
>>
>> At that time, we believed that controlling the feature through netlink
>> was sufficient. However, most people have realized now that netlink is
>> not convenient in container scenarios, and sysctl is a more suitable
>> approach.
>
> Hi D.
>
> thanks for your contribution.
> What i wonder is should we prefer the use of netlink > sysctl or not?
> To the upstream maintainers: Is there a prefernce for the net tree?
>
> My impression from past discussions is that netlink should be chosen 
> over sysctl.
> If so, why is it inconvenient to use netlink in containers?
> Can this be changed?
>
> Other then the general discussion the changhes look good to me.
>
> Reviewed-by: Jan Karcher <jaka@...ux.ibm.com>
>

Hi Jan,

I noticed that there have been relevant discussions before, perhaps this 
will be helpful to you.

Link: https://lore.kernel.org/netdev/20220224020253.GF5443@linux.alibaba.com


Best wishes,
D. Wythe


>
>>
>> In addition, since commit 462791bbfa35 ("net/smc: add sysctl 
>> interface for SMC")
>> had introcuded smc_sysctl_net_init(), it is reasonable for us to
>> initialize limit_smc_hs in it instead of initializing it in
>> smc_pnet_net_int().
>>
>> Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
>> ---
>> v1 -> v2:
>>
>> Modified the description in the commit and removed the incorrect
>> spelling.
>>
>>   net/smc/smc_pnet.c   |  3 ---
>>   net/smc/smc_sysctl.c | 11 +++++++++++
>>   2 files changed, 11 insertions(+), 3 deletions(-)
>>
>> diff --git a/net/smc/smc_pnet.c b/net/smc/smc_pnet.c
>> index 2adb92b..1dd3623 100644
>> --- a/net/smc/smc_pnet.c
>> +++ b/net/smc/smc_pnet.c
>> @@ -887,9 +887,6 @@ int smc_pnet_net_init(struct net *net)
>>         smc_pnet_create_pnetids_list(net);
>>   -    /* disable handshake limitation by default */
>> -    net->smc.limit_smc_hs = 0;
>> -
>>       return 0;
>>   }
>>   diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
>> index 13f2bc0..2fab645 100644
>> --- a/net/smc/smc_sysctl.c
>> +++ b/net/smc/smc_sysctl.c
>> @@ -90,6 +90,15 @@
>>           .extra1        = &conns_per_lgr_min,
>>           .extra2        = &conns_per_lgr_max,
>>       },
>> +    {
>> +        .procname    = "limit_smc_hs",
>> +        .data        = &init_net.smc.limit_smc_hs,
>> +        .maxlen        = sizeof(int),
>> +        .mode        = 0644,
>> +        .proc_handler    = proc_dointvec_minmax,
>> +        .extra1        = SYSCTL_ZERO,
>> +        .extra2        = SYSCTL_ONE,
>> +    },
>>   };
>>     int __net_init smc_sysctl_net_init(struct net *net)
>> @@ -121,6 +130,8 @@ int __net_init smc_sysctl_net_init(struct net *net)
>>       WRITE_ONCE(net->smc.sysctl_rmem, net_smc_rmem_init);
>>       net->smc.sysctl_max_links_per_lgr = SMC_LINKS_PER_LGR_MAX_PREFER;
>>       net->smc.sysctl_max_conns_per_lgr = SMC_CONN_PER_LGR_PREFER;
>> +    /* disable handshake limitation by default */
>> +    net->smc.limit_smc_hs = 0;
>>         return 0;