* Why fio triggers reading of device serial number [not found] <4FB5EA0D.7030402@redhat.com> @ 2012-05-18 6:28 ` Asias He 2012-05-18 10:00 ` Jens Axboe 0 siblings, 1 reply; 3+ messages in thread From: Asias He @ 2012-05-18 6:28 UTC (permalink / raw) To: fio; +Cc: Jens Axboe 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 ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Why fio triggers reading of device serial number 2012-05-18 6:28 ` Why fio triggers reading of device serial number Asias He @ 2012-05-18 10:00 ` Jens Axboe 2012-05-18 14:10 ` Asias He 0 siblings, 1 reply; 3+ messages in thread From: Jens Axboe @ 2012-05-18 10:00 UTC (permalink / raw) To: Asias He; +Cc: fio On 05/18/2012 08:28 AM, Asias He wrote: > 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. Probably mtime changing of the special file inode, causing some udev rule to attempt to re-read the id/serial. Fio doesn't read the serial number. -- Jens Axboe ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Why fio triggers reading of device serial number 2012-05-18 10:00 ` Jens Axboe @ 2012-05-18 14:10 ` Asias He 0 siblings, 0 replies; 3+ messages in thread From: Asias He @ 2012-05-18 14:10 UTC (permalink / raw) To: Jens Axboe; +Cc: fio On 05/18/2012 06:00 PM, Jens Axboe wrote: > On 05/18/2012 08:28 AM, Asias He wrote: >> 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. > > Probably mtime changing of the special file inode, causing some udev > rule to attempt to re-read the id/serial. Fio doesn't read the serial > number. OK. Thanks, Jens. -- Asias ^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] <4FB5EA0D.7030402@redhat.com>
2012-05-18 6:28 ` Why fio triggers reading of device serial number Asias He
2012-05-18 10:00 ` Jens Axboe
2012-05-18 14:10 ` Asias He
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