On Tue, Feb 27, 2018 at 04:21:36PM -0600, Steve Wise wrote:
> >
> > On Mon, Feb 26, 2018 at 03:22:42PM -0800, Steve Wise wrote:
> >
> > > +static int fill_res_mr_entry(struct sk_buff *msg, struct
> netlink_callback
> > *cb,
> > > + struct rdma_restrack_entry *res, uint32_t port)
> > > +{
> > > + struct ib_mr *mr = container_of(res, struct ib_mr, res);
> > > + struct nlattr *entry_attr;
> > > +
> > > + entry_attr = nla_nest_start(msg,
> > RDMA_NLDEV_ATTR_RES_MR_ENTRY);
> > > + if (!entry_attr)
> > > + goto out;
> > > +
> > > + if (netlink_capable(cb->skb, CAP_NET_ADMIN)) {
> > > + if (nla_put_u32(msg, RDMA_NLDEV_ATTR_RES_RKEY, mr-
> > >rkey))
> > > + goto err;
> > > + if (nla_put_u32(msg, RDMA_NLDEV_ATTR_RES_LKEY, mr-
> > >lkey))
> > > + goto err;
> > > + if (nla_put_u64_64bit(msg, RDMA_NLDEV_ATTR_RES_IOVA,
> > > + mr->iova, 0))
> >
> > ?? is '0' right here? Expecting a defined attribute constant for padding.
>
>
> What does the pad do exactly? I replicated other code I saw that use 0 for
> the pad. But I can add a NLDEV_ATTR_RES_PAD if that is the correct way to
> go.
Sometimes netlink will try to align the u64s to 8 bytes in the skb. If
it needs to make an alignment adjustment then it stuffs a dummy
attribute with the given ID. The ID should never be used for any other
attribute and must be ignored by userspace.
Safest to put it in the general enum to ensure it isn't re-used.
> > > + if (nla_put_u32(msg, RDMA_NLDEV_ATTR_RES_PGSIZE, mr-
> > >page_size))
> > > + goto err;
> >
> > Still not really sure what pgsize is supposed to be, I think we should
> > drop it??
> >
>
> Let us say we register a MR that has a backing memory scattergather list of
> 10 64KB entries, each 64KB entry, though, is physically contiguous. The
> page-size for that registration, then can be 64KB even though the host page
> size is 4KB. So the page list for the registration with the rdma device can
> be 10 64K entries, each of size 64KB...
So what is the value?
'max contiguous page size' of any page in the registration or 'min
contiguous page size' of any page in the registration?
Seems like it needs a better name at least..
Jason
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