linux-kernel - Re: [Intel-wired-lan] [PATCH v6 7/7] ixgbevf: eliminate duplicate barriers on weakly-ordered archs

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Date:   Fri, 23 Mar 2018 14:27:28 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>, sulrich@...eaurora.org,
        Netdev <netdev@...r.kernel.org>,
        Timur Tabi <timur@...eaurora.org>,
        LKML <linux-kernel@...r.kernel.org>,
        intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
        linux-arm-msm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [Intel-wired-lan] [PATCH v6 7/7] ixgbevf: eliminate duplicate
 barriers on weakly-ordered archs

On 3/23/2018 2:25 PM, Alexander Duyck wrote:
>> +               /* We need this if more than one processor can write to our tail
>> +                * at a time, it synchronizes IO on IA64/Altix systems
>> +                */
>> +               mmiowb();
>>         }
> The mmiowb shouldn't be needed for Rx. Only one CPU will be running
> NAPI for the queue and we will synchronize this with a full writel
> anyway when we re-enable the interrupts.
> 

OK. I can fix this on the next version. I did a blanket search and replace for
my writel_relaxed() changes as I don't know the code well enough. 

Please point me to the redundant ones.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.