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Date:      Thu, 25 Mar 2010 20:30:56 +0100
From:      Attila Nagy <bra@fsn.hu>
To:        pyunyh@gmail.com
Cc:        Mailing List FreeBSD Stable <freebsd-stable@freebsd.org>
Subject:   Re: 8-STABLE freezes on UDP traffic (DNS), 7.x doesn't
Message-ID:  <4BABB9F0.6010506@fsn.hu>
In-Reply-To: <20100325183628.GD1278@michelle.cdnetworks.com>
References:  <4BAB718C.3090001@fsn.hu> <20100325183628.GD1278@michelle.cdnetworks.com>

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Pyun YongHyeon wrote:
> On Thu, Mar 25, 2010 at 03:22:04PM +0100, Attila Nagy wrote:
>   
>> Hi,
>>
>> I have some recursive nameservers, running unbound and 7.2-STABLE #0: 
>> Wed Sep  2 13:37:17 CEST 2009 on a bunch of HP BL460c machines (bce 
>> interfaces).
>> These work OK.
>>
>> During the process of migrating to 8.x, I've upgraded one of these 
>> machines to 8.0-STABLE #25: Tue Mar  9 18:15:34 CET 2010 (the dates 
>> indicate an approximate time, when the source was checked out from 
>> cvsup.hu.freebsd.org, I don't know the exact revision).
>>
>> The first problem was that the machine occasionally lost network access 
>> for some minutes. I could log in on the console, and I could see the 
>> processes, involved in network IO in "keglim" state, but couldn't do any 
>> network IO. This lasted for some minutes, then everything came back to 
>> normal.
>> I could fix this issue by raising kern.ipc.nmbclusters to 51200 
>> (doubling from its default size), when I can't see these blackouts.
>>
>> But now the machine freezes. It can run for about a day, and then it 
>> just freezes. I can't even break in to the debugger with sending NMI to it.
>> top says:
>> last pid: 92428;  load averages:  0.49,  0.40,  0.38    up 0+21:13:18  
>> 07:41:43
>> 43 processes:  2 running, 38 sleeping, 1 zombie, 2 lock
>> CPU:  1.3% user,  0.0% nice,  1.3% system, 26.0% interrupt, 71.3% idle
>> Mem: 1682M Active, 99M Inact, 227M Wired, 5444K Cache, 44M Buf, 5899M Free
>> Swap:
>>
>>   PID USERNAME   THR PRI NICE   SIZE    RES STATE   C   TIME   WCPU COMMAND
>> 45011 bind         4  49    0  1734M  1722M RUN     2  37:42 22.17% unbound
>>   712 bind         3  44    0 70892K 19904K uwait   0  71:07  3.86% 
>> python2.6
>>
>> The common in these freezes seems to be the high interrupt count. 
>> Normally, during load the CPU times look like this:
>> CPU:  3.5% user,  0.0% nice,  1.8% system,  0.4% interrupt, 94.4% idle
>>
>> I could observe a "freeze", where top remained running and everything 
>> was 0%, except interrupt, which was 25% exactly (the machine has four 
>> cores), and another, where I could save the following console output:
>> CPU:  0.0% user,  0.0% nice,  0.2% system, 50.0% interrupt, 49.8% idle
>>     
>
> When you see high number of interrupts, could you check this comes
> from bce(4)? I guess you can use systat(1) to check how many number
> interrupts are generated from bce(4).
>   
I've tried it multiple times, but couldn't yet catch the moment when the
machine was still alive (so the script could run) and there were
increased amount of interrupts.



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