[Report] requests are submitted to hardware in reverse order from nvme/virtio-blk queue_rqs()

Ming Lei ming.lei at redhat.com
Wed Jan 24 03:59:54 PST 2024


Hello,

Requests are added to plug list in reverse order, and both virtio-blk
and nvme retrieves request from plug list in order, so finally requests
are submitted to hardware in reverse order via nvme_queue_rqs() or
virtio_queue_rqs, see:

	io_uring       submit_bio  vdb      6302096     4096
	io_uring       submit_bio  vdb     12235072     4096
	io_uring       submit_bio  vdb      7682280     4096
	io_uring       submit_bio  vdb     11912464     4096
	io_uring virtio_queue_rqs  vdb     11912464     4096
	io_uring virtio_queue_rqs  vdb      7682280     4096
	io_uring virtio_queue_rqs  vdb     12235072     4096
	io_uring virtio_queue_rqs  vdb      6302096     4096


May this reorder be one problem for virtio-blk and nvme-pci?


Thanks,
Ming




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