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 v1 2/3] RDMA/rw: Support threshold for registration vs scattering to local pages
Date: Mon, 7 Oct 2019 15:36:56 +0300 [thread overview]
Message-ID: <20191007123656.GW5855@unreal> (raw)
In-Reply-To: <20191007121244.GA19843@infradead.org>
On Mon, Oct 07, 2019 at 05:12:44AM -0700, Christoph Hellwig wrote:
> Sorry for nitpicking again, but..
>
> On Mon, Oct 07, 2019 at 02:58:18PM +0300, Leon Romanovsky wrote:
> > @@ -37,15 +39,15 @@ static inline bool rdma_rw_can_use_mr(struct ib_device *dev, u8 port_num)
> > * Check if the device will use memory registration for this RW operation.
> > * We currently always use memory registrations for iWarp RDMA READs, and
> > * have a debug option to force usage of MRs.
> > - *
> > - * XXX: In the future we can hopefully fine tune this based on HCA driver
> > - * input.
>
> The above comment needs an updated a la:
>
> * Check if the device will use memory registration for this RW operation.
> * For RDMA READs we must use MRs on iWarp and can optionaly use them as an
> * optimaztion otherwise. Additionally we have a debug option to force usage
> * of MRs to help testing this code path.
>
>
> > if (rdma_protocol_iwarp(dev, port_num) && dir == DMA_FROM_DEVICE)
> > return true;
> > + if (dev->attrs.max_sgl_rd && dir == DMA_FROM_DEVICE &&
> > + dma_nents > dev->attrs.max_sgl_rd)
> > + return true;
>
> This can be simplified to:
>
> if (dir == DMA_FROM_DEVICE &&
> (rdma_protocol_iwarp(dev, port_num) ||
> (dev->attrs.max_sgl_rd && dma_nents > dev->attrs.max_sgl_rd)))
> return true;
I don't think that it simplifies and wanted to make separate checks to
be separated. For example, rdma_protocol_iwarp() has nothing to do with
attrs.max_sgl_rd.
I'll fix comment.
Thanks
next prev parent reply other threads:[~2019-10-07 12:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-07 11:58 [PATCH rdma-next v1 0/3] Optimize SGL registration Leon Romanovsky
2019-10-07 11:58 ` [PATCH mlx5-next v1 1/3] net/mlx5: Expose optimal performance scatter entries capability Leon Romanovsky
2019-10-07 11:58 ` [PATCH rdma-next v1 2/3] RDMA/rw: Support threshold for registration vs scattering to local pages Leon Romanovsky
2019-10-07 12:12 ` Christoph Hellwig
2019-10-07 12:36 ` Leon Romanovsky [this message]
2019-10-07 12:48 ` Christoph Hellwig
2019-10-07 13:17 ` Leon Romanovsky
2019-10-07 11:58 ` [PATCH rdma-next v1 3/3] RDMA/mlx5: Add capability for max sge to get optimized performance Leon Romanovsky
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