lkml.org 
[lkml]   [2013]   [Feb]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: kswapd craziness round 2
On 18/02/2013 19:42, Hillf Danton wrote:
> On Mon, Feb 18, 2013 at 2:18 PM, Daniel J Blueman
> <daniel@numascale-asia.com> wrote:
>> On Monday, 18 February 2013 06:10:02 UTC+8, Jiri Slaby wrote:
>>
>>> Hi,
>>>
>>> You still feel the sour taste of the "kswapd craziness in v3.7" thread,
>>> right? Welcome to the hell, part two :{.
>>>
>>> I believe this started happening after update from
>>> 3.8.0-rc4-next-20130125 to 3.8.0-rc7-next-20130211. The same as before,
>>> many hours of uptime are needed and perhaps some suspend/resume cycles
>>> too. Memory pressure is not high, plenty of I/O cache:
>>> # free
>>> total used free shared buffers cached
>>> Mem: 6026692 5571184 455508 0 351252 2016648
>>> -/+ buffers/cache: 3203284 2823408
>>> Swap: 0 0 0
>>>
>>> kswap is working very toughly though:
>>> root 580 0.6 0.0 0 0 ? S úno12 46:21 [kswapd0]
>>>
>>> This happens on I/O activity right now. For example by updatedb or find
>>> /. This is what the stack trace of kswapd0 looks like:
>>> [<ffffffff8113c431>] shrink_slab+0xa1/0x2d0
>>> [<ffffffff8113ecd1>] kswapd+0x541/0x930
>>> [<ffffffff810a3000>] kthread+0xc0/0xd0
>>> [<ffffffff816beb5c>] ret_from_fork+0x7c/0xb0
>>> [<ffffffffffffffff>] 0xffffffffffffffff
>>
>> Likewise with 3.8-rc, I've been able to reproduce [1] a livelock scenario
>> which hoses the box and observe RCU stalls [2].
>>
>> There may be a connection; I'll do a bit more debugging in the next few
>> days.
>>
>> Daniel
>>
>> --- [1]
>>
>> 1. live-booted image using ramdisk
>> 2. boot 3.8-rc with <16GB memory and without swap
>> 3. run OpenMP NAS Parallel Benchmark dc.B against local disk (ie not
>> ramdisk)
>> 4. observe hang O(30) mins later
>>
>> --- [2]
>>
>> [ 2675.587878] INFO: rcu_sched self-detected stall on CPU { 5} (t=24000
>> jiffies g=6313 c=6312 q=68)
>
> Does Ingo's revert help? https://lkml.org/lkml/2013/2/15/168

Close, but no cigar; I still hit this livelock on 3.8-rc7 with Ingo's
revert or Linus's fix.

However, I am unable to reproduce the hang with 3.7.9, so will begin
bisection tomorrow, probably automating via pexpect.

Thanks,
Daniel
--
Daniel J Blueman
Principal Software Engineer, Numascale Asia
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2013-02-18 16:41    [W:0.089 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site