On Thu, Feb 25, 2010 at 12:49 PM, Anton Vorontsov
<avoront...@ru.mvista.com> wrote:
> On Thu, Feb 25, 2010 at 07:51:41PM +0300, Anton Vorontsov wrote:
>> On Thu, Feb 25, 2010 at 04:46:54PM +0000, Martyn Welch wrote:
>> [...]
>> > > nfs: server 192.168.0.1 not responding, still trying
>> > >
>> >
>> > Further testing has shown that this isn't restricted to warm reboots, it
>> > happens from cold as well. In addition, the exact timing of the failure
>> > seems to vary, some boots have got further before failing.
>>
>> Unfortunately I don't have any 8641 boards near me, so I can't
>> debug this myself. Though, I tested gianfar on MPC8568E-MDS with
>> 2.6.33 kernel, and it seems to work just fine.
>>
>> I see you use SMP. Can you try to turn it off? If that will fix
>> the issue, then it'll be a good data point.
>>
>> Meanwhile, I'll try SMP kernel on MPC8568 (UP), and let you
>> know the results.
>
> Nope, no luck. Can't trigger the issue. :-/
> Tested with NFS boot, TCP and UDP netperf tests.
I was able to reproduce it on an 8641D and bisected it down to this:
-----------
commit a3bc1f11e9b867a4f49505ecac486a33af248b2e
Author: Anton Vorontsov <avoront...@ru.mvista.com>
Date: Tue Nov 10 14:11:10 2009 +0000
gianfar: Revive SKB recycling
Before calling gfar_clean_tx_ring() the driver grabs an irqsave
spinlock, and then tries to recycle skbs. But since
skb_recycle_check() returns 0 with IRQs disabled, we'll never
recycle any skbs.
It appears that gfar_clean_tx_ring() and gfar_start_xmit() are
mostly idependent and can work in parallel, except when they
modify num_txbdfree.
So we can drop the lock from most sections and thus fix the skb
recycling.
-----------
...which probably explains why you weren't seeing it on non-SMP.
I'd imagine it would show up on any of the e500mc boards too.
I'd done a rev-list on gianfar.[ch] from 32 to 33-rc1, and then
cherry-picked those onto a 32 baseline to reduce the scale of
the bisection, but I don't think that should impact the final
result I got in any meaningful way.
Paul.
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