isp driver - sysctl controls missing

[Ross]

It looks like in the isp(4) driver update that happened back when Freebsd
v8.0 got updated, it looks like the user-modifiable sysctls got
removed and timeouts are now hardcoded.

The man page for isp state:
-=
SYSCTL OPTIONS
     dev.isp.N.loop_down_limit
             This value says how long to wait in seconds after loop has gone
             down before giving up and expiring all of the devices that were
             visible.  The default is 300 seconds (5 minutes).  A seperate
             (nonadjustable) timeout is used when booting to not stop booting
             on lack of FC connectivity.

     dev.isp.N.gone_device_time
             This value says how long to wait for devices to reappear if they
             (temporarily) disappear due to loop or fabric events.  While this
             timeout is running, I/O to those devices will simply be held.

-=

But checking over the driver code shows sysctl details are now removed
and the hardcoded value for loop_down_limit is now 60 seconds and
gone_device_time is 30 seconds.

Anyone know if there's any reason for the sysctl is being pulled out,
and the limits being so high?  We use this in conjunction with geom
multipath, so would prefer to fail over to another fc path asap when
there's an issue.


Cheers,
  Ross.

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