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Date:      Tue, 14 Jun 2011 09:51:44 +1000
From:      Peter Jeremy <peterjeremy@acm.org>
To:        Marius Strobl <marius@alchemy.franken.de>
Cc:        freebsd-sparc64@freebsd.org
Subject:   Re: 'make -j16 universe' gives SIReset
Message-ID:  <20110613235144.GA12470@server.vk2pj.dyndns.org>
In-Reply-To: <20110608224801.GB35494@alchemy.franken.de>
References:  <20110526234728.GA69750@server.vk2pj.dyndns.org> <20110527120659.GA78000@alchemy.franken.de> <20110601231237.GA5267@server.vk2pj.dyndns.org> <20110608224801.GB35494@alchemy.franken.de>

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On 2011-Jun-09 00:48:01 +0200, Marius Strobl <marius@alchemy.franken.de> wr=
ote:
>This might be due to the excessive use of sched_lock by SCHED_4BSD
>and the MD code, f.e. more CPUs means less TLB contexts per CPU which
>in turn means more flushes that are protect by sched_lock.

I have noticed that systat reports very high trap & fault counts.

> It would
>be great if the machine wouldn't lock up so you could check what
>exactly is holding the mutex so long.

Agreed.

>I think meanwhile I had a sound idea how to achieve the necessary level
>of protection in the MD code using just atomic operations instead of
>sched_lock, which further down would also allow the use of SCHED_ULE.

Sounds good - let me know if there's anything I can do to help.

>> I tried adding this and the system survived a "make -j30 universe" on
>> -stable (BTW "make universe" seems to have issues cross-building x86
>> derivatives).  I'm now trying that on -current.  I'm not sure what the
>> implications of the above change are.
>>=20
>
>What was the outcome of these tests?

I got a "spinlock held too long" panic that should have gone to DDB
but the system wouldn't respond to anything other than a RSC reset.

>Nevertheless it also would be interesting to know if you end up
>with a corrupt kernel stack with DDB, KDB and r222840 in place,
>especially in case disabling superscalar dispatch doesn't solve
>the problem.

I'm building r223035 with DDB & KDB and will see how that goes.

--=20
Peter Jeremy

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