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[174.3.196.123]) by smtp.gmail.com with ESMTPSA id q2sm2421082pgf.5.2018.03.13.21.12.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 13 Mar 2018 21:12:55 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.86_2) (envelope-from ) id 1evxmT-0007DX-67; Tue, 13 Mar 2018 22:12:49 -0600 Date: Tue, 13 Mar 2018 22:12:49 -0600 From: Jason Gunthorpe To: Sinan Kaya 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 , Ariel Elior , Doug Ledford , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/7] RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs Message-ID: <20180314041249.GA18314@ziepe.ca> References: <1520997629-17361-1-git-send-email-okaya@codeaurora.org> <1520997629-17361-3-git-send-email-okaya@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1520997629-17361-3-git-send-email-okaya@codeaurora.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > 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 Thanks, Jason