Hi!

I have an update on the "ioctl() takes 16 seconds" issue:

It seems (don't ask me for an explanation) if the buffer size for the SCSI 
response is too small (in my case less than 18 octets), the wsystemcall to read 
the SCSI serial number takes 15-16 seconds, while with a buffer of 18 octets or 
more, it takes 3ms (over an iSCSI-FC-Gateway).

Maybe Mike finds this output of a test program useful:
===================================================
buflen = 17
testprog /dev/sdu 17
SCSI cmd sent: 12  1 80  0 11  0
ioctl duration: 15976 msecs
SCSI response:  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
resplen = 17, pgcode = 0x 0, pglen = 0

/dev/sdu serial no:
:
real    0m15.979s
user    0m0.000s
sys     0m0.000s
===================================================
buflen = 18
testprog /dev/sdu 18
SCSI cmd sent: 12  1 80  0 12  0
ioctl duration: 0 msecs
SCSI response:  0 80  0  e 50 42 35 41 38 44 34 41 41 55 36 38 33 39
resplen = 18, pgcode = 0x80, pglen = 14

/dev/sdu serial no: PB5A8D4AAU6839
:
real    0m0.003s
user    0m0.000s
sys     0m0.000s
===================================================

Regards,
Ulrich

>>> Ulrich Windl schrieb am 24.09.2012 um 08:57 in Nachricht <50600460.815 : 
>>> 161 :
60728>:
> >>> Michael Christie <micha...@cs.wisc.edu> schrieb am 24.09.2012 um 04:46 in
> Nachricht <1f8fae71-ee7c-4785-a648-24758b18e...@cs.wisc.edu>:
> > From what I can tell, it is a dm raid issue or a target issue.
> > 
> > The len dm raid is using might not be right, but I am not sure. I do not 
> > know why the target does not like it.
> > 
> > 
> > On Sep 21, 2012, at 5:59 AM, Ulrich Windl 
> > <ulrich.wi...@rz.uni-regensburg.de> 
> > wrote
> > >> # time sg_inq -e -p 80- /dev/sdc
> > >> unrecognized multiplier
> > >> Bad argument to '--page=', expecting 0 to 255 inclusive
> > >> 
> > >> Modified:
> > >> # time sg_inq -e -p 80 /dev/sdc
> > 
> > I goofed when I wrote the example. You need to pass it in hex so it should 
> > be
> > 
> > sg_inq -e -p 0x80 /dev/sdc
> > 
> > I think that will end up working ok though. sg_inq seems to use a different 
> > len than what dm raid does.
> 
> Hi Mike!
> 
> Thanks for that. Still, that command responds as quick as possible, so maybe 
> it's actually more dmraid than iSCSI.
> 
> # time sg_inq -e -p 0x80 /dev/sdc
> VPD INQUIRY: Unit serial number page
>   Unit serial number: PB5A8D3AATZBSH
> 
> real    0m0.025s
> user    0m0.000s
> sys     0m0.000s
> 
> Regards,
> Ulrich
> 
> 


 

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