[GEDI] [PATCH v7 00/13] blkio: add libblkio BlockDriver
Stefano Garzarella
sgarzare at redhat.com
Wed Oct 19 09:54:42 UTC 2022
I reviewed some patches (the others I do not feel confident of my
knowledge). But I think we are in a very good shape and can merge from
my point of view.
Thanks again for this work,
Stefano
On Thu, Oct 13, 2022 at 02:58:55PM -0400, Stefan Hajnoczi wrote:
>v7:
>- Add nvme-io_uring and virtio-blk-vhost-user syntax examples to commit description [Markus]
>- Add missing nvme-io_uring QAPI [Markus, Alberto]
>- Rename mem-regions-pinned to may-pin-mem-regions [Alberto]
>- Fix value/bs->bl.max_iov mix-up [Stefano]
>v6:
>- Add untested nvme-io_uring driver. Please test in your nested NVMe environment, Alberto. [Alberto]
>- Map blkio mem regions only when necessary to reduce conflicts with RAM discard [Alberto]
>- Reduce duplication by having a single blkio_virtio_blk_common_open() function [Alberto]
>- Avoid duplication in BlockDriver definitions using a macro [Alberto]
>- Avoid ram block registrar segfault [Stefano]
>- Use QLIST_FOREACH_SAFE() in ram block notifier code so callbacks can remove themselves
>v5:
>- Drop "RFC" since libblkio 1.0 has been released and the library API is stable
>- Disable BDRV_REQ_REGISTERED_BUF if we run out of blkio_mem_regions. The
> bounce buffer slow path is taken when there are not enough blkio_mem_regions
> to cover guest RAM. [Hanna & David Hildenbrand]
>- Call ram_block_discard_disable() when mem-region-pinned property is true or
> absent [David Hildenbrand]
>- Use a bounce buffer pool instead of allocating/freeing a buffer for each
> request. This reduces the number of blkio_mem_regions required for bounce
> buffers to 1 and avoids frequent blkio_mem_region_map/unmap() calls.
>- Switch to .bdrv_co_*() instead of .bdrv_aio_*(). Needed for the bounce buffer
> pool's CoQueue.
>v4:
>- Patch 1:
> - Add virtio-blk-vhost-user driver [Kevin]
> - Drop .bdrv_parse_filename() and .bdrv_needs_filename for virtio-blk-vhost-vdpa [Stefano]
> - Add copyright and license header [Hanna]
> - Drop .bdrv_parse_filename() in favor of --blockdev or json: [Hanna]
> - Clarify that "filename" is always non-NULL for io_uring [Hanna]
> - Check that virtio-blk-vhost-vdpa "path" option is non-NULL [Hanna]
> - Fix virtio-blk-vhost-vdpa cache.direct=off logic [Hanna]
> - Use macros for driver names [Hanna]
> - Assert that the driver name is valid [Hanna]
> - Update "readonly" property name to "read-only" [Hanna]
> - Call blkio_detach_aio_context() in blkio_close() [Hanna]
> - Avoid uint32_t * to int * casts in blkio_refresh_limits() [Hanna]
> - Remove write zeroes and discard from the todo list [Hanna]
> - Use PRIu32 instead of %d for uint32_t [Hanna]
> - Fix error messages with buf-alignment instead of optimal-io-size [Hanna]
> - Call map/unmap APIs since libblkio alloc/free APIs no longer do that
> - Update QAPI schema QEMU version to 7.2
>- Patch 5:
> - Expand the BDRV_REQ_REGISTERED_BUF flag passthrough and drop assert(!flags)
> in drivers [Hanna]
>- Patch 7:
> - Fix BLK->BDRV typo [Hanna]
> - Make BlockRAMRegistrar handle failure [Hanna]
>- Patch 8:
> - Replace memory_region_get_fd() approach with qemu_ram_get_fd()
>- Patch 10:
> - Use (void)ret; to discard unused return value [Hanna]
> - libblkio's blkio_unmap_mem_region() API no longer has a return value
> - Check for registered bufs that cross RAMBlocks [Hanna]
>- Patch 11:
> - Handle bdrv_register_buf() errors [Hanna]
>v3:
>- Add virtio-blk-vhost-vdpa for vdpa-blk devices including VDUSE
>- Add discard and write zeroes support
>- Rebase and adopt latest libblkio APIs
>v2:
>- Add BDRV_REQ_REGISTERED_BUF to bs.supported_write_flags [Stefano]
>- Use new blkioq_get_num_completions() API
>- Implement .bdrv_refresh_limits()
>
>This patch series adds a QEMU BlockDriver for libblkio
>(https://gitlab.com/libblkio/libblkio/), a library for high-performance block
>device I/O. This work was presented at KVM Forum 2022 and slides are available
>here:
>https://static.sched.com/hosted_files/kvmforum2022/8c/libblkio-kvm-forum-2022.pdf
>
>The second patch adds the core BlockDriver and most of the libblkio API usage.
>Three libblkio drivers are included:
>- io_uring
>- virtio-blk-vhost-user
>- virtio-blk-vhost-vdpa
>
>The remainder of the patch series reworks the existing QEMU bdrv_register_buf()
>API so virtio-blk emulation efficiently map guest RAM for libblkio - some
>libblkio drivers require that I/O buffer memory is pre-registered (think VFIO,
>vhost, etc).
>
>Vladimir requested performance results that show the effect of the
>BDRV_REQ_REGISTERED_BUF flag. I ran the patches against qemu-storage-daemon's
>vhost-user-blk export with iodepth=1 bs=512 to see the per-request overhead due
>to bounce buffer allocation/mapping:
>
>Name IOPS Error
>bounce-buf 4373.81 ± 0.01%
>registered-buf 13062.80 ± 0.67%
>
>The BDRV_REQ_REGISTERED_BUF optimization version is about 3x faster.
>
>See the BlockDriver struct in block/blkio.c for a list of APIs that still need
>to be implemented. The core functionality is covered.
>
>Regarding the design: each libblkio driver is a separately named BlockDriver.
>That means there is an "io_uring" BlockDriver and not a generic "libblkio"
>BlockDriver. This way QAPI and open parameters are type-safe and mandatory
>parameters can be checked by QEMU.
>
>Stefan Hajnoczi (13):
> coroutine: add flag to re-queue at front of CoQueue
> blkio: add libblkio block driver
> numa: call ->ram_block_removed() in ram_block_notifer_remove()
> block: pass size to bdrv_unregister_buf()
> block: use BdrvRequestFlags type for supported flag fields
> block: add BDRV_REQ_REGISTERED_BUF request flag
> block: return errors from bdrv_register_buf()
> numa: use QLIST_FOREACH_SAFE() for RAM block notifiers
> block: add BlockRAMRegistrar
> exec/cpu-common: add qemu_ram_get_fd()
> stubs: add qemu_ram_block_from_host() and qemu_ram_get_fd()
> blkio: implement BDRV_REQ_REGISTERED_BUF optimization
> virtio-blk: use BDRV_REQ_REGISTERED_BUF optimization hint
>
> MAINTAINERS | 7 +
> meson_options.txt | 2 +
> qapi/block-core.json | 77 +-
> meson.build | 9 +
> include/block/block-common.h | 9 +
> include/block/block-global-state.h | 10 +-
> include/block/block_int-common.h | 15 +-
> include/exec/cpu-common.h | 1 +
> include/hw/virtio/virtio-blk.h | 2 +
> include/qemu/coroutine.h | 15 +-
> include/sysemu/block-backend-global-state.h | 4 +-
> include/sysemu/block-ram-registrar.h | 37 +
> block.c | 14 +
> block/blkio.c | 1008 +++++++++++++++++++
> block/blkverify.c | 4 +-
> block/block-backend.c | 8 +-
> block/block-ram-registrar.c | 58 ++
> block/crypto.c | 4 +-
> block/file-posix.c | 1 -
> block/gluster.c | 1 -
> block/io.c | 101 +-
> block/mirror.c | 2 +
> block/nbd.c | 1 -
> block/nvme.c | 20 +-
> block/parallels.c | 1 -
> block/qcow.c | 2 -
> block/qed.c | 1 -
> block/raw-format.c | 2 +
> block/replication.c | 1 -
> block/ssh.c | 1 -
> block/vhdx.c | 1 -
> hw/block/virtio-blk.c | 39 +-
> hw/core/numa.c | 26 +-
> qemu-img.c | 6 +-
> softmmu/physmem.c | 5 +
> stubs/physmem.c | 13 +
> tests/qtest/modules-test.c | 3 +
> util/qemu-coroutine-lock.c | 9 +-
> util/vfio-helpers.c | 5 +-
> block/meson.build | 2 +
> scripts/meson-buildoptions.sh | 3 +
> stubs/meson.build | 1 +
> 42 files changed, 1435 insertions(+), 96 deletions(-)
> create mode 100644 include/sysemu/block-ram-registrar.h
> create mode 100644 block/blkio.c
> create mode 100644 block/block-ram-registrar.c
> create mode 100644 stubs/physmem.c
>
>--
>2.37.3
>
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