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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> |
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| .. | ||
| accounting.h | ||
| aio-wait.h | ||
| aio.h | ||
| aio_task.h | ||
| block-copy.h | ||
| block-hmp-cmds.h | ||
| block.h | ||
| block_backup.h | ||
| block_int.h | ||
| blockjob.h | ||
| blockjob_int.h | ||
| dirty-bitmap.h | ||
| export.h | ||
| fuse.h | ||
| nbd.h | ||
| nvme.h | ||
| qapi.h | ||
| qdict.h | ||
| raw-aio.h | ||
| replication.h | ||
| snapshot.h | ||
| thread-pool.h | ||
| throttle-groups.h | ||
| write-threshold.h | ||