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Date:      Fri, 4 Jun 2010 08:32:10 -0700
From:      Matthew D Fleming <mdf356@gmail.com>
To:        John Baldwin <jhb@freebsd.org>
Cc:        freebsd-stable@freebsd.org, Clifton Royston <cliftonr@lava.net>, alc@freebsd.org, Garrett Cooper <yanefbsd@gmail.com>, Jeremy Chadwick <freebsd@jdc.parodius.com>
Subject:   Re: Locking a file backed mdconfig into memory
Message-ID:  <20100604153210.GA8522@amaretto>
In-Reply-To: <201006040820.49741.jhb@freebsd.org>
References:  <201005272348.o4RNmgWh014243@hugeraid.jetcafe.org> <201006031029.00588.jhb@freebsd.org> <201006040937.o549bEFt054288@hugeraid.jetcafe.org> <201006040820.49741.jhb@freebsd.org>

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On Fri, Jun 04, 2010 at 08:20:49AM -0400, John Baldwin wrote:
> Hmmm, I would just try increasing NKPT then.  You might have to poke 
> around in sys/amd64 to see what the default size is and how to tune 
> it.

When Isilon did the stable/7 merge and amd64 default NKPT changed from 
240 to 32 amd64 started having weird pmap issues during boot.  At panic 
time the stack wasn't very useful, and I didn't finish debugging the 
issue since eventually I just had to get something working.  We just 
reverted NKPT to 240 and it worked for us.  I didn't see an anything in 
optsions.amd64 so I hard-coded it in amd64/include/pmap.h.

Supposedly amd64 can deal with a small NKPT and grow dynamically, but it 
didn't seem to work for us. :-( Perhaps when we do the next merge 
project I'll have a few days to devote to debugging the root cause.

Thanks,
matthew



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