linux-kernel - Re: Hello and a question about high cpu usage on jfsCommit (kernel 2.6.25.1)

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Date:	Tue, 20 May 2008 09:06:10 -0400
From:	David Fix <davidf@...fx.com>
To:	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
CC:	linux-kernel@...r.kernel.org,
	JFS Discussion <jfs-discussion@...ts.sourceforge.net>
Subject: Re: Hello and a question about high cpu usage on jfsCommit (kernel
 2.6.25.1)

Hey Dave,

Thanks for following up on this...  The previous kernel that I was 
running was 2.6.18.1...  From CentOS 5.1.

It appears that the thread eating up that much CPU isn't a continuous 
happening, only when there's a fair amount of activity going on.  It's 
hard to nail down exactly when it happens, but the next time it does, 
I'll definitely let you all know!

I haven't been able to reboot this machine, as it's a production unit, 
but if I do get the chance, I'll do so.  It seems to have leveled out 
now, with there being no high usage at all on there right now.

    Dave

Dave Kleikamp wrote:
> I'm copying this to jfs-discussion to see if anyone has seen anything
> like this.
>
> On Thu, 2008-05-15 at 15:35 -0400, David Fix wrote:
>   
>> Hey guys,
>>
>> I'm new to the list, but I've been using Linux and fooling around with 
>> the kernel for ages.  :)
>>
>> I've been experiencing high CPU usage for jfsCommit on kernel 2.6.25.1 
>> (haven't had a chance to go to 2.6.25.4, but I didn't see any 
>> JFS-specific changes between the versions yet).
>>     
>
> In fact, there haven't been a whole lot of non-cosmetic changes to jfs
> at all recently.  Nothing I see that suspicious.
>
> What was the previous kernel you were running before moving to 2.6.25.1?
>
>   
>> Here's my hardware 
>> config, as well:
>>
>>
>> CPUs: 2x Intel Xeon E5420 2.5GHz Quad-core
>> RAM: 8GB
>> RAID Controller: 3Ware 9650SE-24M8
>>     
>
> For anyone seeing this for the first time on jfs-discussion, Dave
> followed up stating that this was an x86_64 build.
>
>   
>> I can't find a mention of what motherboard I have in here, so I'll give 
>> a bit of lspci:
>>
>> 00:00.0 Host bridge: Intel Corporation 5000P Chipset Memory Controller 
>> Hub (rev b1)
>> 00:1d.0 USB Controller: Intel Corporation 631xESB/632xESB/3100 Chipset 
>> UHCI USB Controller #1 (rev 09)
>> 00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev d9)
>> 01:00.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express 
>> Upstream Port (rev 01)
>> 03:00.0 PCI bridge: Integrated Device Technology, Inc. Unknown device 
>> 8018 (rev 04) (prog-if 00 [Normal decode])
>> 05:00.0 Ethernet controller: Intel Corporation 82571EB Gigabit Ethernet 
>> Controller (rev 06)
>> 07:00.0 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit 
>> Ethernet Controller (Copper) (rev 01)
>> 0c:00.0 RAID bus controller: 3ware Inc 9650SE SATA-II RAID (rev 01)
>> 0f:0c.0 VGA compatible controller: ATI Technologies Inc ES1000 (rev 02)
>>
>> There's the salient points there.  The NIC is a quad, which is trunked 
>> to the switch using LAPC.
>>
>> I've got a RAID-6 on the 3Ware controller of 20 TB, and when I'm running 
>> "top", I see this:
>>
>> ---
>> top - 15:33:27 up  5:40,  3 users,  load average: 4.33, 3.59, 3.98
>> Tasks: 315 total,   2 running, 313 sleeping,   0 stopped,   0 zombie
>> Cpu(s):  0.2%us, 13.2%sy,  0.0%ni, 61.3%id, 24.9%wa,  0.1%hi,  0.2%si,  
>> 0.0%st
>> Mem:   8194264k total,  8144500k used,    49764k free,     3884k buffers
>> Swap: 16779884k total,      148k used, 16779736k free,  7667400k cached
>>
>>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>>  2669 root      15  -5     0    0    0 R   99  0.0  19:45.71 jfsCommit
>>     
>
> This is highly unusual.  Is this thread continually eating cpu at this
> rate, or does it happen in spurts?
>
>   
>> And people are complaining (and I'm seeing) very slow writes to the drives.
>>
>> Just wondering if anyone has any ideas.  :)  If you need any 
>> information, I'll provide whatever you need.
>>     
>
> Has this happened more than once (have you rebooted and still seen the
> problem)?  I'm not sure if some rare bug has caused some kind of linked
> list corruption that puts the thread into an infinite loop, or if this
> is a real regression.
>
>   
>> Thanks in advance!
>>
>>     Dave
>>     
>
> Thanks,
> Shaggy

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