Hi Anand, On 07/15/2013 02:37 PM, Anand Kumar Santhanam wrote: > Hi Hans, > > Pls find responses inline. > > Regards > Anand > > -----Original Message----- > From: Jack Wang [mailto:xjtuwjp@xxxxxxxxx] > Sent: Monday, July 15, 2013 2:24 PM > To: Hans Verkuil > Cc: Anand Kumar Santhanam; lindar_liu; linux-scsi@xxxxxxxxxxxxxxx; > jinpu.wang@xxxxxxxxxxxxxxxx > Subject: Re: The pm80xx driver hangs in 3.10 with the Adaptec 71605H HBA > > Hi Hans, > On 07/14/2013 10:45 AM, Hans Verkuil wrote: >> Hi Anand, >> >> On 07/12/2013 03:14 PM, Anand Kumar Santhanam wrote: >>> Hans, >>> >>> I reviewed the code changes and I did not see major differences >>> except for the fact that in adaptec driver we have 64 interrupt >>> handlers to handle 64 MSI-X. >>> This was optimized in open src driver to use only 1 interrupt > handler. >>> Can you pls make this change to the open src driver (i.e have >>> multiple interrupt handlers for multiple MSI-X) and check? >> >> I've looked at this more closely, and I wonder whether there isn't a >> race condition here. When an interrupt arrives you put the interrupt >> vector in pm8001_ha->int_vector, then schedule the tasklet. But what >> if two interrupts with different vectors arrive in quick succession >> before the tasklet got a chance to run? In that case the tasklet will > only see the second vector, not the first. Rather scary. >> >> I have not actually seen any issues with this, but by definition race >> conditions are hard to reproduce and I haven't done any serious >> testing with this card. For now I will run with the quick and dirty > msi.diff (http://hverkuil.home.xs4all.nl/msi.diff). >> >> I see two solutions: either use the 64 interrupt handlers as done in >> the adaptec driver, or you can change int_vector into a u64 and use it > >> as a bitmask to record all interrupt vectors that have arrived. > Thanks for looking into this, I think second one is what we want, set > the bitmask when interrupt arrived and clear it when it's processed. > > Anand>> Yes. We will go for the second solution. The multiple > interrupt/tasklet handlers for MSI-X got rejected by the community and > hence > We went for the existing approach. I checked with a single controller > and I did not observe any issues. Also pls note that the open source > driver > Supports only one MSI-X for now and this problem will not occur. > >> >> BTW, another difference between the linux kernel driver and the >> adaptec version are several of the defines in pm8001_defs.h: e.g. >> MPI_QUEUE is 256 in the adaptec driver, while it is 1024 in the kernel > driver. There are other differences as well. >> > Different value may reflect different performance character, but both > should works, there is no one for all setting. > > Anand >> I agree with Jack. I will check on the #defines and get back. > >> Are all the changes in the kernel correct? I would like to have a >> confirmation of that before I am going to trust my data to this > driver. >> >> It clearly hasn't been tested with actual hardware :-( >> > :_( > >>> My sincere apologies. I tested the same with single controller and it > worked fine. However I messed up when submitting > The patches. This was my first open source submission and request you to > bear the inconvenience. Never mind, people make mistake, quickly fix that should be fine. I suggest keep minimal difference between your in house driver and in tree driver, it will make us easy to maintain the driver and make it easy to use for user. Best Regards, Jack -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
