Hi, List I noticed that fio triggers reading of device serial number when fio starts (one read) and stops (lots of read). I was wondering if fio was reading the sysfs attribute directly in fio's code, e.g./sys/block/vda/serial, or it triggered something which make udevd to read it. trace-cmd shows it seems udevd is reading: udevd-6856 [006] xxx: function: dev_attr_show udevd-6856 [006] xxx: function: virtblk_serial_show Any ideas? Thanks. UDEV RULES --------------- /lib/udev/rules.d/60-persistent-storage.rules KERNEL=="vd*[!0-9]", ATTRS{serial}=="?*", ENV{ID_SERIAL}="$attr{serial}", SYMLINK+="disk/by-id/virtio-$env{ID_SERIAL}" KERNEL=="vd*[0-9]", ATTRS{serial}=="?*", ENV{ID_SERIAL}="$attr{serial}", SYMLINK+="disk/by-id/virtio-$env{ID_SERIAL}-part%n" FIO Config ------------- [global] bs=512 size=100G direct=1 #ioengine=libaio ioengine=sync numjobs=256 filename=/dev/vda thread [seq-read-write] rw=rw -- Asias -- 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