From: Logan Gunthorpe Subject: Re: [PATCH v2 01/21] scatterlist: Introduce sg_map helper functions Date: Thu, 27 Apr 2017 09:57:58 -0600 Message-ID: References: <1493144468-22493-1-git-send-email-logang@deltatee.com> <1493144468-22493-2-git-send-email-logang@deltatee.com> <20170426074416.GA7936@lst.de> <4736d44e-bbcf-5d59-a1a9-317d0f4da847@deltatee.com> <20170427065338.GA20677@lst.de> <20170427152720.GA7662@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: linux-nvdimm-y27Ovi1pjclAfugRpC6u6w@public.gmane.org, dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, target-devel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Sumit Semwal , devel-gWbeCf7V1WCQmaza687I9mD2FQJk+8+b@public.gmane.org, "James E.J. Bottomley" , linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Matthew Wilcox , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, open-iscsi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, intel-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org, sparmaintainer-GLv8BlqOqDDQT0dZR+AlfA@public.gmane.org, linux-raid-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, megaraidlinux.pdl-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, Jens Axboe , "Martin K. Petersen" , Greg Kroah-Hartman , linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-crypto-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jason Gunthorpe , Christoph Hellwig Return-path: In-Reply-To: <20170427152720.GA7662-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-crypto.vger.kernel.org On 27/04/17 09:27 AM, Jason Gunthorpe wrote: > On Thu, Apr 27, 2017 at 08:53:38AM +0200, Christoph Hellwig wrote: > How about first switching as many call sites as possible to use > sg_copy_X_buffer instead of kmap? Yeah, I could look at doing that first. One problem is we might get more Naks of the form of Herbert Xu's who might be concerned with the performance implications. These are definitely a bit more invasive changes than thin wrappers around kmap calls. > A random audit of Logan's series suggests this is actually a fairly > common thing. It's not _that_ common but there are a significant fraction. One of my patches actually did this to two places that seemed to be reimplementing the sg_copy_X_buffer logic. Thanks, Logan