Hi, I am using fio for benchmarking random read IOPS of files. (Test configuration is listed at the bottom.) I have traced I/Os from fio by systemtap and noticed that the number of I/Os at scsi level is twice as many as the number of I/Os at vfs level. But, I/O size at both scsi level and vfs level shown as 4KB, so simply measured 1/2 performance. I also tried by benchmarking tools and the same issue happend. so, it's not fio specific issue. But, I am wondering if any of you knows the reason for that or some hints. Test configuration. ================= ioengine=psync rw=randread numjobs=1 blocksize=4096 filename=file_morethan_100G thread runtime=60 randrepeat=0 ================= (I clean up page caches every time before mesurement.) Thanks, Hiroyuki -- 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
