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.
> > 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. > 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 :-( > :_( Thanks, Jack > Regards, > > Hans > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
