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Date: Wed, 14 Mar 2018 08:06:32 -0400
From: okaya@codeaurora.org
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: netdev@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org,
        linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Michal Kalderon <Michal.Kalderon@cavium.com>,
        Ariel Elior <Ariel.Elior@cavium.com>,
        Doug Ledford <dledford@redhat.com>, linux-rdma@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/7] RDMA/qedr: eliminate duplicate barriers on
 weakly-ordered archs
In-Reply-To: <20180314041249.GA18314@ziepe.ca>
References: <1520997629-17361-1-git-send-email-okaya@codeaurora.org>
 <1520997629-17361-3-git-send-email-okaya@codeaurora.org>
 <20180314041249.GA18314@ziepe.ca>
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On 2018-03-14 00:12, Jason Gunthorpe wrote:
> On Tue, Mar 13, 2018 at 11:20:24PM -0400, Sinan Kaya wrote:
>> Code includes wmb() followed by writel() in multiple places. 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@codeaurora.org>
>>  drivers/infiniband/hw/qedr/verbs.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> Sure matches my understanding of writel_relaxed
> 
> This is part of a series, should we take just this patch through the
> rdma tree? If not:
> 
> Acked-by: Jason Gunthorpe <jgg@mellanox.com>

Feel free to take pieces.


> 
> Thanks,
> Jason