benchmarking - How fio benchmark tool performs sequential disk reads? -


i use fio test read/write bandwidth of disks.

even sequential read test, can let run multiple threads.

what mean running multiple threads on sequential read test?

  • does perform multiple sequential reads? (each thread assigned file offset start sequential scanning from)

  • do multiple threads share file offset? (each thread invokes sequential reads using single file offset shared multiple threads)

i tried read open source codes of fio, couldn't figure out.

can 1 give me idea?

sadly didn't include jobfile question , didn't platform you're running on. here's stab @ answers:

  • yes multiple sequential reads though wouldn't have single thread?
  • no each thread has own offset.

on linux fio defaults using separate processes per job , each process has own file descriptor (for ioengines use files) each file used. further, ioengines (e.g. libaio, pvsync there many others) use syscalls take offset want i/o @ request if share descriptor offset not impacted others using same descriptor.

there may problems if use sync ioengine, ask fio use threads rather process , have threads work on same file. ioengine has use lseek prior doing i/o perhaps there's chance thread's lseek sneak in before i/o submitted. note sync i/o engine not default 1 used recent fio versions.

perhaps fio mailing list can more?


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