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Re: [RFC v4 11/11] virtio-blk: use BDRV_REQ_REGISTERED_BUF optimization
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From: |
David Hildenbrand |
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Subject: |
Re: [RFC v4 11/11] virtio-blk: use BDRV_REQ_REGISTERED_BUF optimization hint |
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Date: |
Tue, 23 Aug 2022 10:01:59 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 |
On 23.08.22 00:24, Stefan Hajnoczi wrote:
> Register guest RAM using BlockRAMRegistrar and set the
> BDRV_REQ_REGISTERED_BUF flag so block drivers can optimize memory
> accesses in I/O requests.
>
> This is for vdpa-blk, vhost-user-blk, and other I/O interfaces that rely
> on DMA mapping/unmapping.
Can you explain why we're monitoring RAMRegistrar to hook into "guest
RAM" and not go the usual path of the MemoryListener?
What will BDRV_REQ_REGISTERED_BUF actually do? Pin all guest memory in
the worst case such as io_uring fixed buffers would do ( I hope not ).
--
Thanks,
David / dhildenb
- Re: [RFC v4 01/11] blkio: add libblkio block driver, (continued)
- [RFC v4 02/11] numa: call ->ram_block_removed() in ram_block_notifer_remove(), Stefan Hajnoczi, 2022/08/22
- [RFC v4 04/11] block: use BdrvRequestFlags type for supported flag fields, Stefan Hajnoczi, 2022/08/22
- [RFC v4 03/11] block: pass size to bdrv_unregister_buf(), Stefan Hajnoczi, 2022/08/22
- [RFC v4 05/11] block: add BDRV_REQ_REGISTERED_BUF request flag, Stefan Hajnoczi, 2022/08/22
- [RFC v4 07/11] block: add BlockRAMRegistrar, Stefan Hajnoczi, 2022/08/22
- [RFC v4 06/11] block: return errors from bdrv_register_buf(), Stefan Hajnoczi, 2022/08/22
- [RFC v4 08/11] exec/cpu-common: add qemu_ram_get_fd(), Stefan Hajnoczi, 2022/08/22
- [RFC v4 09/11] stubs: add qemu_ram_block_from_host() and qemu_ram_get_fd(), Stefan Hajnoczi, 2022/08/22
- [RFC v4 11/11] virtio-blk: use BDRV_REQ_REGISTERED_BUF optimization hint, Stefan Hajnoczi, 2022/08/22
- Re: [RFC v4 11/11] virtio-blk: use BDRV_REQ_REGISTERED_BUF optimization hint,
David Hildenbrand <=
[RFC v4 10/11] blkio: implement BDRV_REQ_REGISTERED_BUF optimization, Stefan Hajnoczi, 2022/08/22
Re: [RFC v4 00/11] blkio: add libblkio BlockDriver, Vladimir Sementsov-Ogievskiy, 2022/08/23