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 (12):
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()
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 | 53 +-
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 | 1017 +++++++++++++++++++
block/blkverify.c | 4 +-
block/block-backend.c | 8 +-
block/block-ram-registrar.c | 54 +
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 | 17 +
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, 1412 insertions(+), 91 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
