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Date: Fri, 27 Mar 2015 18:35:28 +0100
Message-ID: <CAJuTgQUFXLdaj=+6baamUvPHC4Ocj4f_U6Q5WD9UijbaZ3iYLg@mail.gmail.com>
Subject: Re: [RFC PATCH 08/11] IB/Verbs: Use management helper has_iwarp()
 for, iwarp-check
From: Yun Wang <yun.wang@profitbricks.com>
To: "ira.weiny" <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>,
        Roland Dreier <roland@kernel.org>, Sean Hefty <sean.hefty@intel.com>,
        Hal Rosenstock <hal.rosenstock@gmail.com>,
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On Fri, Mar 27, 2015 at 6:16 PM, ira.weiny <ira.weiny@intel.com> wrote:
> On Fri, Mar 27, 2015 at 10:13:19AM -0600, Jason Gunthorpe wrote:
>> On Fri, Mar 27, 2015 at 04:47:36PM +0100, Michael Wang wrote:
>> >
>> > Introduce helper has_iwarp() to help us check if an IB device
>> > support IWARP protocol.
>>
>> Should probably be !has_rdma_read_sges()
>>
>> True if the device can handle more than one SGE entry on a RDMA READ
>> work request.
>
> Isn't this value already provided by the query_device verb?
>
> The verbs spec states the Query HCA contains the:
>
> "Maximum number of scatter/gather entries per Work Request supported by the
> HCA."

I'm not sure but may be query_device() is just too expensive for this path?
I need some investigation here too.

Regards,
Michael Wang

>
> -- Ira
>
>>
>> Jason