Re: [PATCH rdma-next 3/3] RDMA/rw: Support threshold for registration vs scattering to local pages

From: Leon Romanovsky <leon@kernel.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Doug Ledford <dledford@redhat.com>,
	Jason Gunthorpe <jgg@mellanox.com>,
	RDMA mailing list <linux-rdma@vger.kernel.org>,
	Or Gerlitz <ogerlitz@mellanox.com>,
	Yamin Friedman <yaminf@mellanox.com>,
	Saeed Mahameed <saeedm@mellanox.com>,
	linux-netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH rdma-next 3/3] RDMA/rw: Support threshold for registration vs scattering to local pages
Date: Mon, 7 Oct 2019 10:54:37 +0300	[thread overview]
Message-ID: <20191007075437.GV5855@unreal> (raw)
In-Reply-To: <20191007065825.GA17401@infradead.org>

On Sun, Oct 06, 2019 at 11:58:25PM -0700, Christoph Hellwig wrote:
> >  /*
> > - * Check if the device might use memory registration.  This is currently only
> > - * true for iWarp devices. In the future we can hopefully fine tune this based
> > - * on HCA driver input.
> > + * Check if the device might use memory registration.
> >   */
>
> Please keep the important bits of this comments instead of just
> removing them.
>
> >  {
> > @@ -30,6 +28,8 @@ static inline bool rdma_rw_can_use_mr(struct ib_device *dev, u8 port_num)
> >  		return true;
> >  	if (unlikely(rdma_rw_force_mr))
> >  		return true;
> > +	if (dev->attrs.max_sgl_rd)
> > +		return true;
>
> Logically this should go before the rdma_rw_force_mr check.
>
> >  	if (unlikely(rdma_rw_force_mr))
> >  		return true;
> > +	if (dev->attrs.max_sgl_rd && dir == DMA_FROM_DEVICE
> > +	    && dma_nents > dev->attrs.max_sgl_rd)
>
> Wrong indendation.  The && belongs on the first line.  And again, this
> logically belongs before the rdma_rw_force_mr check.

I'll fix.

Thanks