[openib-general] [mthca] Creation of a SRQ with many WR (> 16K) in kernel level fails

[Michael S. Tsirkin]

> Quoting Dotan Barak <dotanb at dev.mellanox.co.il>:
> Subject: Re: [mthca] Creation of a SRQ with many WR (> 16K) in kernel level fails
> 
> Roland Dreier wrote:
> >  > anyway, the solution that comes into my mind is to disable creating a
> >  > QP/SRQ for which > 128KB allocations are needed. So
> >  > mthca_query_device() will set the max_qp_wr and max_srq_wr attributes
> >  > to values whose derived size still allows to use kmalloc.
> >
> > But that will limit the size of the queues that userspace can create
> > too.  I guess we could allocate kernel wrid arrays with vmalloc(), but
> > I wonder if anyone actually cares about this limit...
>
> I think that now, when implementation of IPoIB CM is available and SRQ 
> is being used, one may need to use a SRQ with more than 16K WRs.

Not really: IPoIB CM uses a common CQ for all recv completions, so
it does not make sense for IPoIB CM to create a SRQ bigger than
the max CQ size.

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MST