On 08/02/2013 02:59 PM, Julian Freed wrote:
> 
> Thanks for the patch.
> After few tests I believe it solves the problem, after restoring  
> #define CONTEXT_POOL_MAX 32
> 

Thanks for testing.

> Two more questions.
> 
> I need to increase the lun_limit, currently it is limited to 511
> 
> I thought I found the limit   in  kernel/iscsi_tcp.c      static
> unsigned int iscsi_max_lun = 512
> But changing this, that did not help.

Did you change the code or use the modparam that the code is for? What
kernel is this with too? There is a weird kink with older kernels and
that modparam. You had to set the param then do login. You also cannot
write to the sysfs file. You had to do it modprobe time.

> The file in the kernel 3.8.4 seems to be unlimited         static
> unsigned int iscsi_max_lun = ~0;
> By the way the file in the kernel is very different from open-iscsi-2.0-873
> 

Yeah, the 512 limit in the old code was just a artificial limit. We used
to hit bugs with older targets that would not respond to inquirys and
report luns like how the scsi layer wanted it, so the scsi layer would
drop down to sequential scans that took a long time. Those targets are
longer really used and so the limit was removed in newer kernels.



> 
> Another question:
> Why the iscsi login is so slow.   It takes 40 seconds for 900 iscsi luns
> in 3 targets.
> 

Is the iscsi login slow or the device setup and discovery? When you run
the iscsiadm login we do both. The iscsi login should be fast. Send the
/var/log/messages so I can check.

The device setup and discovery for 900 luns is probably slow. The scsi
layer sends lots of commands to find luns and set them up. In newer
kernels we do some of the setup in parrallel so that should help if your
kernel has it on. It is still slow for 900 luns though.

It seems you are used to looking at the source so if interested see
sd_probe_async. The iscsi layer already does scsi scanning for each
target async so ignore the scsi async scanning stuff.

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