Reworking of GPU reset logic

[Christian König]

On 20.04.2012 01:47, Jerome Glisse wrote:
> 2012/4/19 Christian König<deathsimple at vodafone.de>:
>> This includes mostly fixes for multi ring lockups and GPU resets, but it should general improve the behavior of the kernel mode driver in case something goes badly wrong.
>>
>> On the other hand it completely rewrites the IB pool and semaphore handling, so I think there are still a couple of problems in it.
>>
>> The first four patches were already send to the list, but the current set depends on them so I resend them again.
>>
>> Cheers,
>> Christian.
> I did a quick review, it looks mostly good, but as it's sensitive code
> i would like to spend sometime on
> it. Probably next week. Note that i had some work on this area too, i
> mostly want to drop all the debugfs
> related to this and add some new more usefull (basicly something that
> allow you to read all the data
> needed to replay a locking up ib). I also was looking into Dave reset
> thread and your solution of moving
> reset in ioctl return path sounds good too but i need to convince my
> self that it encompass all possible
> case.
>
> Cheers,
> Jerome
>
After sleeping a night over it I already reworked the patch for 
improving the SA performance, so please wait at least for v2 before 
taking a look at it :)

Regarding the debugging of lockups I had the following on my "in mind 
todo" list:
1. Rework the chip specific lockup detection code a bit more and 
probably clean it up a bit.
2. Make the timeout a module parameter, cause compute task sometimes 
block a ring for more than 10 seconds.
3. Keep track of the actually RPTR offset a fence is emitted to
3. Keep track of all the BOs a IB is touching.
4. Now if a lockup happens start with the last successfully signaled 
fence and dump the ring content after that RPTR offset till the first 
not signaled fence.
5. Then if this fence references to an IB dump it's content and the BOs 
it is touching.
6. Dump everything on the ring after that fence until you reach the RPTR 
of the next fence or the WPTR of the ring.
7. If there is a next fence repeat the whole thing at number 5.

If I'm not completely wrong that should give you practically every 
information available, and we probably should put that behind another 
module option, cause we are going to spam syslog pretty much here. Feel 
free to add/modify the ideas on this list.

Christian.