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

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Message-ID: <d21add89-7298-4574-9873-44c8e9dd8075@linux.alibaba.com>
Date: Fri, 16 Aug 2024 10:06:12 +0800
From: "D. Wythe" <alibuda@...ux.alibaba.com>
To: Wen Gu <guwen@...ux.alibaba.com>, kgraul@...ux.ibm.com,
 wenjia@...ux.ibm.com, jaka@...ux.ibm.com, wintera@...ux.ibm.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] net/smc: add sysctl for smc_limit_hs



On 8/15/24 9:14 PM, Wen Gu wrote:
>
>
> On 2024/8/15 21:03, 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.
>>
>> In addition, it is not reasonable for us to initialize limit_smc_hs in
>> smc_pnet_net_init, we made a mistable before. It should be initialized
>
> nit: mistable -> mistake?

Take it. Also, I suddenly realized that the reason for initializing 
limit_smc_hs in smc_pnet_net_init before
was because there was no smc_sysctl_net_init at that time ...

D. Wythe

>
>> in smc_sysctl_net_init(), just like other systcl.
>>
>> Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
>> ---
>>   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;