Re: [PATCH rdma-next v1 1/6] IB/uverbs: Allow CQ moderation with modify CQ

Leon Romanovsky
2017-10-29T18:28:08Z

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On Sun, Oct 29, 2017 at 11:43:45AM -0600, Jason Gunthorpe wrote:
> On Sun, Oct 29, 2017 at 03:51:35PM +0200, Leon Romanovsky wrote:
> > From: Yonatan Cohen <yonatanc-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> >
> > Uverbs support in modify_cq for CQ moderation only.
> > Gives ability to change cq_max_count and cq_period.
> > CQ moderation enhance performance by moderating the number
> > of cookies needed to create an event instead of application
> > having to suffer from event per cookie.
>
>
> Like the other recent uAPI patches, lets us see the rdma-core side and
> man page first please.

Yishai planned to send it tomorrow.

>
> Can you organize all of them into a rdma-core branch someplace?
>
> Not really sure what a cookie is, or why this should be needed when we
> already have the means to indicate if CQE's should be signalled or
> not.

It is my fault, I forgot to change cookie to be CQE.

>
> I guess it is for UD applications where the existing signalled stuff
> isn't applicable?
>
> > +int ib_uverbs_ex_modify_cq(struct ib_uverbs_file *file,
> > + struct ib_device *ib_dev,
> > + struct ib_udata *ucore,
> > + struct ib_udata *uhw)
>
> Is this really a good idea?
>
> Why not ib_uverbs_set_cq_moderation ?

It follows already existed ib_modify_cq(), see commit 2dd571622787 ("IB/core: Add support for modify CQ")

>
> We don't have to keep making these thicker and thicker APIs if there
> isn't a reason :(
>
> Jason

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