From: Jens Axboe <axboe@kernel.dk>
To: Meelis Roos <mroos@linux.ee>, Christoph Hellwig <hch@infradead.org>
Cc: linux-scsi@vger.kernel.org, sparclinux@vger.kernel.org,
David Miller <davem@davemloft.net>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: Another (ESP?) scsi blk-mq problem on sparc64
Date: Fri, 14 Nov 2014 12:42:40 -0700 [thread overview]
Message-ID: <54665B30.4070708@kernel.dk> (raw)
In-Reply-To: <alpine.LRH.2.11.1411142114200.26813@adalberg.ut.ee>
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
next prev parent reply other threads:[~2014-11-14 19:42 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-14 11:32 Another (ESP?) scsi blk-mq problem on sparc64 Meelis Roos
2014-11-14 16:58 ` Christoph Hellwig
2014-11-14 17:01 ` Jens Axboe
2014-11-14 19:35 ` Meelis Roos
2014-11-14 19:42 ` Jens Axboe [this message]
2014-11-14 22:59 ` Meelis Roos
2014-11-14 23:29 ` Jens Axboe
2014-11-15 6:48 ` Meelis Roos
2014-11-15 15:31 ` Jens Axboe
2014-11-20 6:01 ` Christoph Hellwig
2014-11-21 19:56 ` David Miller
2014-11-24 8:21 ` Christoph Hellwig
2014-11-24 15:35 ` Jens Axboe
2014-11-24 16:22 ` Paul E. McKenney
2014-11-24 17:16 ` Jens Axboe
2014-11-24 17:31 ` Paul E. McKenney
2014-11-24 17:33 ` Jens Axboe
2014-11-24 17:44 ` Paul E. McKenney
2014-11-24 21:56 ` David Miller
2014-11-24 22:01 ` Jens Axboe
2014-11-24 22:09 ` David Miller
2014-11-24 22:20 ` Jens Axboe
2014-11-24 22:23 ` mroos
2014-11-24 22:28 ` David Miller
2015-01-29 7:53 ` Meelis Roos
2015-01-29 16:37 ` Jens Axboe
2015-09-04 8:33 ` Meelis Roos
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