* 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
end of thread, other threads:[~2012-05-18 14:10 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
[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
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.