Re: [PATCH v4 01/13] Linux RDMA Core Changes

[Michael S. Tsirkin]

> > 
> > No, it won't need 2 transitions - just an extra function call,
> > so it won't hurt performance - it would improve performance.
> > 
> > ib_uverbs_req_notify_cq would call
> > 
> > 	ib_uverbs_req_notify_cq()
> > 	{
> > 			ib_set_cq_udata(cq, udata)
> > 			ib_req_notify_cq(cq, cmd.solicited_only ?
> > 				IB_CQ_SOLICITED : IB_CQ_NEXT_COMP);
> > 	}
> > 
> 
> ib_set_cq_udata() would transition into the kernel to pass in the
> consumer's index.  In addition, ib_req_notify_cq would also transition
> into the kernel since its not a bypass function for chelsio.

We misunderstand each other.

ib_uverbs_req_notify_cq is in drivers/infiniband/core/uverbs_cmd.c -
all this code runs inside the IB_USER_VERBS_CMD_REQ_NOTIFY_CQ command,
so there is a single user to kernel transition.

-- 
MST
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