On 11/14/2014 12:35 PM, Meelis Roos wrote: >> Paul, what's the best way to figure out these CPU stalls? >> >> The second oops is in blk_mq_map_queue() which is a trivial >> two level cpu lookup. I wonder if there's something odd about >> cpu numbers on these big old sparc systems? > > CPU numbers are sparse - they are determined by hardware slot number and > some models only fill every other mainboard slot, and first slots can be > free. I have first board offline and currently have CPUs numbered > 10,11,14,15 online. > > Here is debug with Jens's patch:
> [ 133.971050] CPU 11: synchronized TICK with master CPU (last diff -1 > cycles, maxerr 516 cycles) > [ 133.975491] CPU 14: synchronized TICK with master CPU (last diff -3 > cycles, maxerr 531 cycles) > [ 133.979943] CPU 15: synchronized TICK with master CPU (last diff -3 > cycles, maxerr 531 cycles) > [ 133.980146] Brought up 4 CPUs So this looks like this might be the issue. On a scsi-mq disabled boot, you have 4 CPUs, but how are they numbered? We might need Christophs debug patch on top this to fully know... -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
