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Demonstrations of biosnoop, the Linux BPF/bpftrace version. This traces block I/O, and shows the issuing process (at least, the process that was on-CPU at the time of queue insert) and the latency of the I/O: # ./biosnoop.bt Attaching 4 probes... TIME(ms) DISK COMM PID LAT(ms) 611 nvme0n1 bash 4179 10 611 nvme0n1 cksum 4179 0 627 nvme0n1 cksum 4179 15 641 nvme0n1 cksum 4179 13 644 nvme0n1 cksum 4179 3 658 nvme0n1 cksum 4179 13 673 nvme0n1 cksum 4179 14 686 nvme0n1 cksum 4179 13 701 nvme0n1 cksum 4179 14 710 nvme0n1 cksum 4179 8 717 nvme0n1 cksum 4179 6 728 nvme0n1 cksum 4179 10 735 nvme0n1 cksum 4179 6 751 nvme0n1 cksum 4179 10 758 nvme0n1 cksum 4179 17 783 nvme0n1 cksum 4179 12 796 nvme0n1 cksum 4179 25 802 nvme0n1 cksum 4179 32 [...] This output shows the cksum process was issuing block I/O, which were completing with around 12 milliseconds of latency. Each block I/O event is printed out, with a completion time as the first column, measured from program start. An example of some background flushing: # ./biosnoop.bt Attaching 4 probes... TIME(ms) DISK COMM PID LAT(ms) 2966 nvme0n1 jbd2/nvme0n1-8 615 0 2967 nvme0n1 jbd2/nvme0n1-8 615 0 [...] There is another version of this tool in bcc: https://github.com/iovisor/bcc The bcc version provides more fields.