[PATCH] Add locking to twe(4) so it no longer uses Giant

[Garrett Cooper]

On Aug 3, 2012, at 1:42 PM, Mike Tancsa wrote:

> On 8/3/2012 3:39 PM, John Baldwin wrote:
>> On Friday, August 03, 2012 2:56:00 pm Kevin Oberman wrote:
>>> I'll try to find time to try it later today, but I'm in the middle of
>>> budget wrangling and I can't make any promises.
>>> 
>>> Before I try, will these patches apply to the twe driver in
>>> 9.1-PRERELEASE? My system with twe was updated to RELENG_9 on July 18.
>>> I really don't have time to install current right now.
>> 
>> I believe the patches should apply fine on 8 and 9.  If you use it on 8 or 9
>> please make sure to enable INVARIANTS and INVARIANT_SUPPORT at least for
>> initial testing.  Thanks!
> 
> Seems to apply to RELENG_9 just fine.  Are there any stress tests you
> suggest I run that might expose some bugs ? The machine is not
> production yet, so its ok to crash it.

	Looking really quickly at the patch, it looks like most of the locking changes are made around management pieces, and not data handling pieces (but I might have missed something).
	If there's a tool for poking at the drives/controller, I would use that, plus camcontrol. Of course you want a data intensive workload (iometer/iozone/xdd with async and sync mode, random reads and sequential reads, etc), and maybe resort to manual testing like pulling drives (power, data) if you don't mind creating failures. If you have some failed/failing drives kicking around, that would be a good test as well (see that all/some of the failure paths are properly stimulated).
	Any variance or combining of these tests will help build confidence in the change being proposed.
HTH,
-Garrett