netdev - Re: [PATCH net-next v2] net/smc: Use percpu ref for wr tx reference

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <a1516a5e-4d8b-f00c-cecd-e1b2f124fdcd@linux.alibaba.com>
Date:   Wed, 1 Mar 2023 09:44:41 +0800
From:   Kai <KaiShen@...ux.alibaba.com>
To:     Wenjia Zhang <wenjia@...ux.ibm.com>,
        Guangguan Wang <guangguan.wang@...ux.alibaba.com>,
        kgraul@...ux.ibm.com, jaka@...ux.ibm.com
Cc:     kuba@...nel.org, davem@...emloft.net, netdev@...r.kernel.org,
        linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org
Subject: Re: [PATCH net-next v2] net/smc: Use percpu ref for wr tx reference



On 2023/2/28 8:52 下午, Wenjia Zhang wrote:
> 
> 
> On 28.02.23 13:15, Guangguan Wang wrote:
>>
>> On 2023/2/28 19:34, Kai wrote:
>>>
>>>
>>> On 2023/2/28 6:55 下午, Wenjia Zhang wrote:
>>>
>>>> @Kai, the performance improvement seems not so giant, but the method 
>>>> looks good, indeed. However, to keep the consistency of the code, 
>>>> I'm wondering why you only use the perf_ref for wr_tx_wait, but not 
>>>> for wr_reg_refcnt?
>>> Didn't check the similar refcnt, my bad.
>>> On the other hand, Our work is inspired by performance analysis, it 
>>> seems wr_reg_refcnt is not on the IO path. It may not contribute to 
>>> performance improvement.
>>> And inspired by your comment, it seems we can also make the refcnt 
>>> cdc_pend_tx_wr a perfcpu one. I will look into this.
>>>
>>> Thanks
>>
>> cdc_pend_tx_wr needs to be zero value tested every time it decreases 
>> in smc_cdc_tx_handler.
>> I don't think this is the right scenario for percpu_ref.
> 
> I agree, that's why I didn't mention it;)
> 
> But could you please check about wr_reg_refcnt? Because we do need to 
> find the right balance between the code consistency and improvement
Will do