ab42f35d9c
Before blk-mq is introduced, I/O is merged to elevator before being putted into plug queue, but blk-mq changed the order and makes merging to sw queue basically impossible. Then it is observed that throughput of sequential I/O is degraded about 10%~20% on virtio-blk in the test[1] if mq-deadline isn't used. This patch moves the bio merging per sw queue before plugging, like what blk_queue_bio() does, and the performance regression is fixed under this situation. [1]. test script: sudo fio --direct=1 --size=128G --bsrange=4k-4k --runtime=40 --numjobs=16 --ioengine=libaio --iodepth=64 --group_reporting=1 --filename=/dev/vdb --name=virtio_blk-test-$RW --rw=$RW --output-format=json RW=read or write Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com> |
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| drivers | ||
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| fs | ||
| include | ||
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| ipc | ||
| kernel | ||
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| samples | ||
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| security | ||
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| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| README | ||
README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.