Re: [PATCH libibverbs v2 3/3] Provide remote XRC SRQ number in kernel post_send.

[Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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On Mon, Sep 19, 2016 at 11:12:36AM +0200, Knut Omang wrote:
> On Mon, 2016-09-19 at 08:29 +0300, Leon Romanovsky wrote:
> > On Sat, Sep 17, 2016 at 05:59:13AM +0200, Knut Omang wrote:
> > >
> > > Also proper end align the ibv_kern_send_wr struct.
> > >
> > > Requires a corresponding kernel change.
> > >
> > > Signed-off-by: Knut Omang <knut.omang-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> > > Reviewed-by: Mukesh Kacker <mukesh.kacker-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
> > > ---
> > >  include/infiniband/kern-abi.h | 1 +
> > >  src/cmd.c                     | 2 ++
> > >  2 files changed, 3 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/include/infiniband/kern-abi.h b/include/infiniband/kern-abi.h
> > > index 8bdeef5..7b1d310 100644
> > > --- a/include/infiniband/kern-abi.h
> > > +++ b/include/infiniband/kern-abi.h
> > > @@ -800,6 +800,7 @@ struct ibv_kern_send_wr {
> > >  	union {
> > >  		struct {
> > >  			__u32 remote_srqn;
> > > +			__u32 reserved;
> > >  		} xrc;
> > >  	} qp_type;
> > >  };
> > > diff --git a/src/cmd.c b/src/cmd.c
> > > index a418ee1..a4e2f75 100644
> > > --- a/src/cmd.c
> > > +++ b/src/cmd.c
> > > @@ -1293,6 +1293,8 @@ int ibv_cmd_post_send(struct ibv_qp *ibqp, struct ibv_send_wr *wr,
> > >  			tmp->wr.ud.remote_qpn  = i->wr.ud.remote_qpn;
> > >  			tmp->wr.ud.remote_qkey = i->wr.ud.remote_qkey;
> > >  		} else {
> > > +			if (ibqp->qp_type == IBV_QPT_XRC_SEND)
> > > +				tmp->qp_type.xrc.remote_srqn = i->qp_type.xrc.remote_srqn;
> > It will be checked for all QPTs and for all consumers. Any chances to
> > optimize it?
>
> All QPTs except UD, yes.
>
> The easiest is perhaps just to remove the test (and set the attribute in all cases), which will work fine
> as long as the qp_type union is not used for anything else, but is it worth 
> the loss of intuitiveness/future potential correctness of the code?

Let's concentrate on the present and as far as I see there are no kernel users who
need this field xrc.remote_srqn field.

>
> Note that this is for user mode post_send implemented by the kernel, not the "fast path"
> pure user mode.
>
> Knut
>
> > >
> > >  			switch (i->opcode) {
> > >  			case IBV_WR_RDMA_WRITE:
> > >  			case IBV_WR_RDMA_WRITE_WITH_IMM:
> > > --
> > > git-series 0.8.10
> > > --
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