linux-kernel - Re: [Intel-wired-lan] [PATCH v3 09/18] fm10k: Eliminate duplicate barriers on weakly-ordered archs

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Date:   Fri, 16 Mar 2018 12:33:14 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     Netdev <netdev@...r.kernel.org>, Timur Tabi <timur@...eaurora.org>,
        sulrich@...eaurora.org, linux-arm-msm@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [Intel-wired-lan] [PATCH v3 09/18] fm10k: Eliminate duplicate
 barriers on weakly-ordered archs

On 3/16/2018 12:30 PM, Alexander Duyck wrote:
> On Fri, Mar 16, 2018 at 9:16 AM, Sinan Kaya <okaya@...eaurora.org> wrote:
>> Code includes wmb() followed by writel(). writel() already has a
>> barrier on some architectures like arm64.
>>
>> This ends up CPU observing two barriers back to back before executing
>> the register write.
>>
>> Since code already has an explicit barrier call, changing writel() to
>> writel_relaxed().
>>
>> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> 
> You can update the writel call in fm10k_tx_map as well.
> 
> Of the drivers updated in drivers/net/ethernet/intel/* it looks like
> this is the only one that still requires any additional changes.

will do. thanks for the feedback.

> 
> Thanks.
> 
> - Alex
> 


-- 
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.