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| author | Paolo Bonzini <pbonzini@redhat.com> | 2021-06-03 10:34:23 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-06-25 10:54:13 +0200 |
| commit | 24b36e9813ec15da7db62e3b3621730710c5f020 (patch) | |
| tree | a164db85c4e52bdda0190aaf5752168df6337795 /include/sysemu | |
| parent | b99f7fa08a3df8b8a6a907642e5851cdcf43fa9f (diff) | |
| download | qemu-24b36e9813ec15da7db62e3b3621730710c5f020.zip qemu-24b36e9813ec15da7db62e3b3621730710c5f020.tar.gz qemu-24b36e9813ec15da7db62e3b3621730710c5f020.tar.bz2 | |
block: add max_hw_transfer to BlockLimits
For block host devices, I/O can happen through either the kernel file
descriptor I/O system calls (preadv/pwritev, io_submit, io_uring)
or the SCSI passthrough ioctl SG_IO.
In the latter case, the size of each transfer can be limited by the
HBA, while for file descriptor I/O the kernel is able to split and
merge I/O in smaller pieces as needed. Applying the HBA limits to
file descriptor I/O results in more system calls and suboptimal
performance, so this patch splits the max_transfer limit in two:
max_transfer remains valid and is used in general, while max_hw_transfer
is limited to the maximum hardware size. max_hw_transfer can then be
included by the scsi-generic driver in the block limits page, to ensure
that the stricter hardware limit is used.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/sysemu')
| -rw-r--r-- | include/sysemu/block-backend.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h index 5423e3d..9ac5f7b 100644 --- a/include/sysemu/block-backend.h +++ b/include/sysemu/block-backend.h @@ -208,6 +208,7 @@ void blk_eject(BlockBackend *blk, bool eject_flag); int blk_get_flags(BlockBackend *blk); uint32_t blk_get_request_alignment(BlockBackend *blk); uint32_t blk_get_max_transfer(BlockBackend *blk); +uint64_t blk_get_max_hw_transfer(BlockBackend *blk); int blk_get_max_iov(BlockBackend *blk); void blk_set_guest_block_size(BlockBackend *blk, int align); void *blk_try_blockalign(BlockBackend *blk, size_t size); |