From mboxrd@z Thu Jan 1 00:00:00 1970 From: "santosh.shilimkar-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org" Subject: Re: [PATCH 0/9] IB: Optimize DMA mapping Date: Tue, 10 Jan 2017 17:28:14 -0800 Message-ID: <320aa1cd-8110-2724-a43d-514efc386127@oracle.com> References: <20170111005648.14988-1-bart.vanassche@sandisk.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170111005648.14988-1-bart.vanassche-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Bart Van Assche , Doug Ledford Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org On 1/10/17 4:56 PM, Bart Van Assche wrote: > Hello Doug, > > As you know there are two sets of DMA mapping operations in the Linux > kernel: > - One set of DMA mapping operations that is used by most drivers. > - Another set of DMA mapping operations that is only used by the RDMA > drivers. > Having two sets of DMA mapping operations is not only a source of > confusion but also a source of unnecessary overhead. The DMA mapping > operations are in the hot path so it is important that the overhead > of these operations is as low as possible. Hence this patch series > that converts the RDMA code to the standard DMA mapping API and > thereby eliminates the if (dev->dma_ops) test from the hot path. An > additional benefit is that the size of HW and SW drivers that do not > use DMA is reduced by switching to dma_virt_ops. > This is really good series. I was always wondering why the extra indirection was added first place on streaming APIs. Regards, Santosh -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html