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Date:   Tue, 17 May 2022 11:59:49 -0300
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     longli@microsoft.com
Cc:     "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Leon Romanovsky <leon@kernel.org>,
        linux-hyperv@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org
Subject: Re: [PATCH 05/12] net: mana: Set the DMA device max page size
Message-ID: <20220517145949.GH63055@ziepe.ca>
References: <1652778276-2986-1-git-send-email-longli@linuxonhyperv.com>
 <1652778276-2986-6-git-send-email-longli@linuxonhyperv.com>
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On Tue, May 17, 2022 at 02:04:29AM -0700, longli@linuxonhyperv.com wrote:
> From: Long Li <longli@microsoft.com>
> 
> The system chooses default 64K page size if the device does not specify
> the max page size the device can handle for DMA. This do not work well
> when device is registering large chunk of memory in that a large page size
> is more efficient.
> 
> Set it to the maximum hardware supported page size.

For RDMA devices this should be set to the largest segment size an
ib_sge can take in when posting work. It should not be the page size
of MR. 2M is a weird number for that, are you sure it is right?

Jason