2012/3/30 Chuck Tuffli <ctuffli@xxxxxxxxx>: > I've been testing disk performance using fio, and am seeing results I > can't explain. This may not necessarily be a problem with fio, or > perhaps I'm not using the some of the parameters correctly. The > testing uses the latest fio.git on a RHEL system running a 2.6.32 > kernel. > > The fio test is: > > fio --name=global --ioengine=libaio --rw=read --bs=512 --size=500m > --iodepth=32 --direct=1 --filename=/dev/sdb --name=job1 > > The IOPs reported in this case appears to correlate with an external analyzer. > > If I change the iodepth to 64, fio reports double the IOPs reported in > the previous case, but the performance measured by the analyzer is the > same as in the iodepth=32 case (i.e. half what fio reports). I tried > the iodepth=64 case with another disk performance tool, and it is > reporting the same results as the external analyzer. > > Interestingly, using iodepth=32 and adding a second job (--name=job2) > seems to have the same effect as iodepth=64 (reported performance is > 2x compared to the external analyzer). > > Am I doing something obviously wrong? What else can/should I check? TIA > > ---chuck > -- > To unsubscribe from this list: send the line "unsubscribe fio" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html Can you see the same result if using --rw=randread? -- Regards, Zhu Yanhai -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
