Re: NUMA Autobalancing Kernel 3.8

[Stefan Priebe - Profihost AG <s.priebe@profihost.ag>]

Am 02.04.2013 14:54, schrieb Mel Gorman:
> On Tue, Apr 02, 2013 at 01:41:34PM +0200, Stefan Priebe - Profihost AG wrote:
>> Am 02.04.2013 12:48, schrieb Mel Gorman:
>>> On Tue, Apr 02, 2013 at 09:24:51AM +0200, Stefan Priebe - Profihost AG wrote:
>>>> Hello list,
>>>>
>>>> i was trying to play with the new NUMA autobalancing feature of Kernel 3.8.
>>>>
>>>> But if i enable:
>>>> CONFIG_ARCH_USES_NUMA_PROT_NONE=y
>>>> CONFIG_NUMA_BALANCING_DEFAULT_ENABLED=y
>>>> CONFIG_NUMA_BALANCING=y
>>>>
>>>> i see random process crashes mostly in libc using vanilla 3.8.4.
>>>>
>>>
>>> Any more details than that? What sort of crashes? Anything in the kernel
>>> log? Any particular pattern to the crashes? Any means of reliably
>>> reproducing it? 3.8 vanilla, 3.8-stable or 3.8 with any other patches
>>> applied?
>>
>> Sorry for missing information.
>>
>>> Any more details than that?
>> Sadly not i just see a crash line in the kernel log - see below.
>>
>>> What sort of crashes?
>> Mostly the processes just die but i've also seen processes consuming
>> 100% CPU all the time or even just doing nothing anymore.
>>
> 
> When you see the 100% CPU usage can you cat /proc/PID/stack a couple of
> times and post it here? That might give a hint as to where it's going wrong.

Sadly i'm not able to reproduce a 100% load process tried now for some
hours. Mostly they segfault.

>>> Anything in the kernel log?
>> Three examples:
>> pigz[10194]: segfault at 0 ip           (null) sp 00007f6197ffed50 error
>> 14 in pigz[400000+e000]
>>
>> rbd[2811]: segfault at b8 ip 00007f73c2d51b9e sp 00007f73bcae3b40 error
>> 4 in librados.so.2.0.0[7f73c2afe000+3b9000]
>>
>> rbd[1805]: segfault at 0 ip 00007f60c28dceb4 sp 00007f60b7ffd1f8 error 4
>> in ld-2.11.3.so[7f60c28cc000+1e000]
>>
>>> Any particular pattern to the crashes? Any means of reliably
>>> reproducing it?
>> No i just need to run some task and after some time they die or hang
>> forever. I have this on 10 different E5-2640 and also on E56XX. I can
>> "fix" this by:
>>   1.) putting all memory to just ONE CPU
>>   2.) Disable NUMA Balancing
>>
> That does point the finger at the automatic balancing.
> 
>>> 3.8 vanilla, 3.8-stable or 3.8 with any other patches
>>> applied?
>> 3.8.4 without any patches.
>>
> Did it happen in 3.8?

I've now tested 3.9-rc5 this gaves me a slightly different kernel log:
[  197.236518] pigz[2908]: segfault at 0 ip           (null) sp
00007f347bffed00 error 14
[  197.237632] traps: pigz[2915] general protection ip:7f3482dbce2d
sp:7f3473ffec10 error:0 in libz.so.1.2.3.4[7f3482db7000+17000]
[  197.330615]  in pigz[400000+10000]

With 3.8 it is the same as with 3.8.4 or 3.8.5.

Greets,
Stefan

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>