On Mon, Apr 25, 2016 at 09:16:18AM -0700, Bart Van Assche wrote: > On 04/25/2016 08:53 AM, Leon Romanovsky wrote: > >On Mon, Apr 25, 2016 at 12:46:59PM +0300, Sagi Grimberg wrote: > >> > >>>>>>+ max_max_sectors = (srp_dev->max_pages_per_mr - 1) << > >>>>>>+ (ilog2(srp_dev->mr_page_size) - 9); > >>>>> > >>>>> From my understanding, srp_dev->max_pages_per_mr can be equal to 1, in > >>>>>case device will advertise it. > >>>>> > >>>>>Is this understanding correct? > >>>>>Will the code work in such case? > >>>> > >>>>Hello Leon, > >>>> > >>>>I'm not sure a HCA driver exists for which max_pages_per_mr == 1. > >>>>Additionally, I'm not sure such a driver would be useful because such a > >>>>driver would limit the maximum data transfer size for the iSER protocol to 4 > >>>>KB. That is too low to reach good performance. > >>> > >>>Bart and Laurence, > >>>You are raising valuable arguments about sanity of setting srp_dev->max_pages_per_mr > >>>to be equal 1. I totally agree with you that it is insane, however my > >>>original question was "does the code support such value?" > >> > >>I don't see why we should worry about imaginary devices. > > > >It is called corner case and the code supports it. > > I can add a WARN_ON_ONCE() statement for max_pages_per_mr == 1. That will > make it easy to figure out where to start looking if in the future a HCA > driver would be added that causes max_pages_per_mr == 1. > Thanks Bart, It is fair enough. > Bart.
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