From: Christoph Hellwig <hch@lst.de>
To: Eric Dumazet <edumazet@google.com>
Cc: Jonathan Lemon <jonathan.lemon@gmail.com>,
netdev <netdev@vger.kernel.org>, kernel-team <kernel-team@fb.com>,
Christoph Hellwig <hch@lst.de>,
Robin Murphy <robin.murphy@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
David Miller <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Willem de Bruijn <willemb@google.com>,
Steffen Klassert <steffen.klassert@secunet.com>,
Saeed Mahameed <saeedm@mellanox.com>,
Maxim Mikityanskiy <maximmi@mellanox.com>,
bjorn.topel@intel.com, magnus.karlsson@intel.com,
borisp@mellanox.com, david@redhat.com
Subject: Re: [RFC PATCH v2 15/21] net/tcp: add MSG_NETDMA flag for sendmsg()
Date: Tue, 28 Jul 2020 08:50:29 +0200 [thread overview]
Message-ID: <20200728065029.GA21479@lst.de> (raw)
In-Reply-To: <CANn89iL=p3pgDpPeWz5rZqGeCdHg=X=hkEPe=mk9TDa=bk7ZRQ@mail.gmail.com>
On Mon, Jul 27, 2020 at 07:17:51PM -0700, Eric Dumazet wrote:
> > The thing is, the existing zero copy code is zero-copy to /host/ memory,
> > which is not the same thing as zero-copy to other memory areas.
>
> You have to really explain what difference it makes, and why current
> stuff can not be extended.
There basically is none. You need to call a different dma mapping
routine and make sure to never access the device pages. See
drivers/pci/p2pdma.c and its users for an example on how to do it
properly. But the author wants all his crazy hacks to hook into his
proprietary crap, so everyone should be ignore this horrible series.
next prev parent reply other threads:[~2020-07-28 6:50 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200727052846.4070247-1-jonathan.lemon@gmail.com>
[not found] ` <20200727052846.4070247-4-jonathan.lemon@gmail.com>
2020-07-27 5:58 ` [RFC PATCH v2 03/21] mm: Allow DMA mapping of pages which are not online Christoph Hellwig
2020-07-27 17:08 ` Jonathan Lemon
[not found] ` <20200727052846.4070247-22-jonathan.lemon@gmail.com>
2020-07-27 7:35 ` [RFC PATCH v2 21/21] netgpu/nvidia: add Nvidia plugin for netgpu Christoph Hellwig
2020-07-27 17:00 ` Jonathan Lemon
2020-07-27 18:24 ` Christoph Hellwig
2020-07-28 1:48 ` Jonathan Lemon
2020-07-28 6:47 ` Christoph Hellwig
2020-07-28 16:05 ` Jonathan Lemon
2020-07-28 16:10 ` Christoph Hellwig
2020-07-28 18:19 ` Jason Gunthorpe
2020-07-28 21:01 ` Jonathan Lemon
2020-07-28 21:14 ` Christoph Hellwig
2020-07-28 23:38 ` Jason Gunthorpe
[not found] ` <20200727052846.4070247-14-jonathan.lemon@gmail.com>
2020-07-27 15:19 ` [RFC PATCH v2 13/21] net/tcp: Pad TCP options out to a fixed size " Eric Dumazet
2020-07-27 17:20 ` Jonathan Lemon
[not found] ` <20200727052846.4070247-16-jonathan.lemon@gmail.com>
2020-07-27 15:19 ` [RFC PATCH v2 15/21] net/tcp: add MSG_NETDMA flag for sendmsg() Eric Dumazet
2020-07-27 15:55 ` Jonathan Lemon
2020-07-27 16:09 ` Eric Dumazet
2020-07-27 17:35 ` Jonathan Lemon
2020-07-27 17:44 ` Eric Dumazet
2020-07-28 2:11 ` Jonathan Lemon
2020-07-28 2:17 ` Eric Dumazet
2020-07-28 3:08 ` Jonathan Lemon
2020-07-28 6:50 ` Christoph Hellwig [this message]
[not found] ` <20200727052846.4070247-9-jonathan.lemon@gmail.com>
2020-07-27 15:24 ` [RFC PATCH v2 08/21] skbuff: add a zc_netgpu bitflag Eric Dumazet
2020-07-27 16:59 ` Jonathan Lemon
2020-07-27 17:08 ` Eric Dumazet
2020-07-27 17:16 ` Jonathan Lemon
2020-07-27 22:44 [RFC PATCH v2 00/21] netgpu: networking between NIC and GPU/CPU Jonathan Lemon
2020-07-27 22:44 ` [RFC PATCH v2 15/21] net/tcp: add MSG_NETDMA flag for sendmsg() Jonathan Lemon
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