On Fri, Dec 4, 2015 at 7:40 AM, Robert Kierski <rkierski@xxxxxxxx> wrote: > It turns out the problem I'm experiencing is related to thread count. When I run XDD with a reasonable queuedepth parameter (32), I get horrible performance. When I run it with a small queuedepth (1-4), I get expected performance. > > Here are the command lines: > > Horrible Performance: > xdd -id commandline -dio -maxall -targets 1 /dev/md0 -queuedepth 32 -blocksize 1048576 -timelimit 10 -reqsize 1 -mbytes 5000 -passes 20 -verbose -op write -seek sequential > > GOOD Performance: > xdd -id commandline -dio -maxall -targets 1 /dev/md0 -queuedepth 1 -blocksize 1048576 -timelimit 10 -reqsize 1 -mbytes 5000 -passes 20 -verbose -op write -seek sequential > > BEST Performance: > xdd -id commandline -dio -maxall -targets 1 /dev/md0 -queuedepth 3 -blocksize 1048576 -timelimit 10 -reqsize 1 -mbytes 5000 -passes 20 -verbose -op write -seek sequential > > BAD Performance > xdd -id commandline -dio -maxall -targets 1 /dev/md1 -queuedepth 5 -blocksize 1048576 -timelimit 10 -reqsize 1 -mbytes 5000 -passes 20 -verbose -op write -seek sequential > > Bob Kierski > Senior Storage Performance Engineer > Cray Inc. > 380 Jackson Street > Suite 210 > St. Paul, MN 55101 > Tele: 651-967-9590 > Fax: 651-605-9001 > Cell: 651-890-7461 > Robert, is this with a RAID 6 array? Also, what are the actual throughput numbers you are getting? Would it be possible for you to capture the iostat -xm output and report the individual disk wMB/s and also the disk utilization for RAID 6? -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
