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From: Christoph Hellwig <hch@lst.de>
To: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
Cc: "Christoph Hellwig" <hch@lst.de>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"maximmi@mellanox.com" <maximmi@mellanox.com>,
	"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
	"jonathan.lemon@gmail.com" <jonathan.lemon@gmail.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"magnus.karlsson@intel.com" <magnus.karlsson@intel.com>
Subject: Re: [PATCH net] xsk: remove cheap_dma optimization
Date: Wed, 8 Jul 2020 14:19:40 +0200	[thread overview]
Message-ID: <20200708121940.GA19619@lst.de> (raw)
In-Reply-To: <B926444035E5E2439431908E3842AFD255E99A@DGGEMI525-MBS.china.huawei.com>

On Wed, Jul 08, 2020 at 07:57:23AM +0000, Song Bao Hua (Barry Song) wrote:
> > int dma_map_batch_start(struct device *dev, size_t rounded_len,
> > 	enum dma_data_direction dir, unsigned long attrs, dma_addr_t *addr);
> > int dma_map_batch_add(struct device *dev, dma_addr_t *addr, struct page
> > *page,
> > 		unsigned long offset, size_t size);
> > int dma_map_batch_end(struct device *dev, int ret, dma_addr_t start_addr);
> > 
> 
> Hello Christoph,
> 
> What is the different between dma_map_batch_add() and adding the buffer to sg of dma_map_sg()?

There is not struct scatterlist involved in this API, avoiding the
overhead to allocate it (which is kinda the point).

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: "Song Bao Hua (Barry Song)" <song.bao.hua@hisilicon.com>
Cc: "maximmi@mellanox.com" <maximmi@mellanox.com>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"jonathan.lemon@gmail.com" <jonathan.lemon@gmail.com>,
	"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Christoph Hellwig" <hch@lst.de>,
	"magnus.karlsson@intel.com" <magnus.karlsson@intel.com>
Subject: Re: [PATCH net] xsk: remove cheap_dma optimization
Date: Wed, 8 Jul 2020 14:19:40 +0200	[thread overview]
Message-ID: <20200708121940.GA19619@lst.de> (raw)
In-Reply-To: <B926444035E5E2439431908E3842AFD255E99A@DGGEMI525-MBS.china.huawei.com>

On Wed, Jul 08, 2020 at 07:57:23AM +0000, Song Bao Hua (Barry Song) wrote:
> > int dma_map_batch_start(struct device *dev, size_t rounded_len,
> > 	enum dma_data_direction dir, unsigned long attrs, dma_addr_t *addr);
> > int dma_map_batch_add(struct device *dev, dma_addr_t *addr, struct page
> > *page,
> > 		unsigned long offset, size_t size);
> > int dma_map_batch_end(struct device *dev, int ret, dma_addr_t start_addr);
> > 
> 
> Hello Christoph,
> 
> What is the different between dma_map_batch_add() and adding the buffer to sg of dma_map_sg()?

There is not struct scatterlist involved in this API, avoiding the
overhead to allocate it (which is kinda the point).
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  reply	other threads:[~2020-07-08 12:19 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-26 13:43 [PATCH net] xsk: remove cheap_dma optimization Björn Töpel
2020-06-26 13:43 ` Björn Töpel
2020-06-26 20:44 ` Jonathan Lemon
2020-06-26 20:44   ` Jonathan Lemon
2020-06-26 23:00 ` Daniel Borkmann
2020-06-26 23:00   ` Daniel Borkmann
2020-06-27  7:04   ` Christoph Hellwig
2020-06-27  7:04     ` Christoph Hellwig
2020-06-28 17:16     ` Björn Töpel
2020-06-28 17:16       ` Björn Töpel
2020-06-29 13:52       ` Daniel Borkmann
2020-06-29 13:52         ` Daniel Borkmann
2020-06-29 15:10         ` Björn Töpel
2020-06-29 15:10           ` Björn Töpel
2020-06-29 15:18           ` Daniel Borkmann
2020-06-29 15:18             ` Daniel Borkmann
2020-06-29 16:23             ` Björn Töpel
2020-06-29 16:23               ` Björn Töpel
2020-06-30  5:07             ` Christoph Hellwig
2020-06-30  5:07               ` Christoph Hellwig
2020-06-30 13:47               ` Daniel Borkmann
2020-06-30 13:47                 ` Daniel Borkmann
2020-06-29 15:41       ` Robin Murphy
2020-06-29 15:41         ` Robin Murphy
2020-07-01 10:17         ` Björn Töpel
2020-07-01 10:17           ` Björn Töpel
2020-07-08  6:50         ` Christoph Hellwig
2020-07-08  6:50           ` Christoph Hellwig
2020-07-08  7:57           ` Song Bao Hua (Barry Song)
2020-07-08  7:57             ` Song Bao Hua (Barry Song)
2020-07-08 12:19             ` Christoph Hellwig [this message]
2020-07-08 12:19               ` Christoph Hellwig
2020-07-08 13:18           ` Robin Murphy
2020-07-08 13:18             ` Robin Murphy

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