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Re: [Qemu-devel] [Qemu-block] [PATCH v3 3/6] block: Introduce bdrv_dma_m
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap |
Date: |
Tue, 11 Jul 2017 11:05:35 +0100 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
On Mon, Jul 10, 2017 at 05:08:56PM +0200, Paolo Bonzini wrote:
> On 10/07/2017 17:07, Stefan Hajnoczi wrote:
> > On Wed, Jul 05, 2017 at 09:36:32PM +0800, Fam Zheng wrote:
> >> Allow block driver to map and unmap a buffer for later I/O, as a
> >> performance
> >> hint.
> > The name blk_dma_map() is confusing since other "dma" APIs like
> > dma_addr_t and dma_blk_io() deal with guest physical addresses instead
> > of host addresses. They are about DMA to/from guest RAM.
> >
> > Have you considered hiding this cached mapping in block/nvme.c so that
> > it isn't exposed? block/nvme.c could keep the last buffer mapped and
> > callers would get the performance benefit without a new blk_dma_map()
> > API.
>
> One buffer is enough for qemu-img bench, but not for more complex cases
> (e.g. fio).
I don't see any other blk_dma_map() callers.
Stefan
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- [Qemu-devel] [PATCH v3 0/6] block: Add VFIO based driver for NVMe device, Fam Zheng, 2017/07/05
- [Qemu-devel] [PATCH v3 1/6] stubs: Add stubs for ram block API, Fam Zheng, 2017/07/05
- [Qemu-devel] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap, Fam Zheng, 2017/07/05
- Re: [Qemu-devel] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap, Stefan Hajnoczi, 2017/07/10
- Re: [Qemu-devel] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap, Stefan Hajnoczi, 2017/07/10
- Re: [Qemu-devel] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap, Paolo Bonzini, 2017/07/10
- Re: [Qemu-devel] [Qemu-block] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap,
Stefan Hajnoczi <=
- Re: [Qemu-devel] [Qemu-block] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap, Paolo Bonzini, 2017/07/11
- Re: [Qemu-devel] [Qemu-block] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap, Fam Zheng, 2017/07/11
- Re: [Qemu-devel] [Qemu-block] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap, Paolo Bonzini, 2017/07/12
- Re: [Qemu-devel] [Qemu-block] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap, Stefan Hajnoczi, 2017/07/14
- Re: [Qemu-devel] [Qemu-block] [PATCH v3 3/6] block: Introduce bdrv_dma_map and bdrv_dma_unmap, Paolo Bonzini, 2017/07/14
[Qemu-devel] [PATCH v3 2/6] block: Add VFIO based NVMe driver, Fam Zheng, 2017/07/05