From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Ira Weiny <ira.weiny@intel.com>,
Christopher Lameter <cl@linux.com>,
john.hubbard@gmail.com, Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, Al Viro <viro@zeniv.linux.org.uk>,
Christian Benvenuti <benve@cisco.com>,
Christoph Hellwig <hch@infradead.org>,
Dan Williams <dan.j.williams@intel.com>,
Dennis Dalessandro <dennis.dalessandro@intel.com>,
Doug Ledford <dledford@redhat.com>, Jan Kara <jack@suse.cz>,
Jason Gunthorpe <jgg@ziepe.ca>,
Jerome Glisse <jglisse@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Michal Hocko <mhocko@kernel.org>,
Mike Rapoport <rppt@linux.ibm.com>,
Mike Marciniszyn <mike.marciniszyn@intel.com>,
Ralph Campbell <rcampbell@nvidia.com>,
Tom Talpey <tom@talpey.com>, LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel@vger.kernel.org, John Hubbard <jhubbard@nvidia.com>
Subject: Re: [PATCH v3 0/1] mm: introduce put_user_page*(), placeholder versions
Date: Wed, 13 Mar 2019 09:03:19 -0700 [thread overview]
Message-ID: <20190313160319.GA15134@infradead.org> (raw)
In-Reply-To: <20190312221113.GF23020@dastard>
On Wed, Mar 13, 2019 at 09:11:13AM +1100, Dave Chinner wrote:
> On Tue, Mar 12, 2019 at 03:39:33AM -0700, Ira Weiny wrote:
> > IMHO I don't think that the copy_file_range() is going to carry us through the
> > next wave of user performance requirements. RDMA, while the first, is not the
> > only technology which is looking to have direct access to files. XDP is
> > another.[1]
>
> Sure, all I doing here was demonstrating that people have been
> trying to get local direct access to file mappings to DMA directly
> into them for a long time. Direct Io games like these are now
> largely unnecessary because we now have much better APIs to do
> zero-copy data transfer between files (which can do hardware offload
> if it is available!).
And that is just the file to file case. There are tons of other
users of get_user_pages, including various drivers that do large
amounts of I/O like video capture. For them it makes tons of sense
to transfer directly to/from a mmap()ed file.
next prev parent reply other threads:[~2019-03-13 16:03 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-06 23:54 [PATCH v3 0/1] mm: introduce put_user_page*(), placeholder versions john.hubbard
2019-03-06 23:54 ` [PATCH v3 1/1] " john.hubbard
2019-03-08 2:58 ` Christopher Lameter
2019-03-08 3:15 ` John Hubbard
2019-03-08 17:43 ` Weiny, Ira
2019-03-08 17:57 ` Jerome Glisse
2019-03-08 21:27 ` John Hubbard
2019-03-12 15:30 ` Ira Weiny
2019-03-13 0:38 ` John Hubbard
2019-03-13 14:49 ` Ira Weiny
2019-03-14 3:19 ` John Hubbard
2019-03-07 8:37 ` [PATCH v3 0/1] " Ira Weiny
2019-03-08 3:08 ` Christopher Lameter
2019-03-08 19:07 ` Jerome Glisse
2019-03-12 4:52 ` Christopher Lameter
2019-03-12 15:35 ` Jerome Glisse
2019-03-12 15:53 ` Jason Gunthorpe
2019-03-13 19:16 ` Christopher Lameter
2019-03-13 19:33 ` Jerome Glisse
2019-03-14 9:03 ` Jan Kara
2019-03-14 12:57 ` Jason Gunthorpe
2019-03-14 13:30 ` Jan Kara
2019-03-14 20:25 ` William Kucharski
2019-03-14 20:37 ` John Hubbard
2019-03-10 22:47 ` Dave Chinner
2019-03-12 5:23 ` Christopher Lameter
2019-03-12 10:39 ` Ira Weiny
2019-03-12 22:11 ` Dave Chinner
2019-03-12 15:23 ` Ira Weiny
2019-03-13 16:03 ` Christoph Hellwig [this message]
2019-03-13 19:21 ` Christopher Lameter
2019-03-14 9:06 ` Jan Kara
2019-03-18 20:12 ` John Hubbard
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