High load, lots of free memory and processes in devfs state

Stut stuttle at gmail.com
Mon Jun 16 21:28:09 UTC 2008


On 16 Jun 2008, at 22:20, Patrick C wrote:
> Is the MySQL daemon still running on that box? I see a mysqldump but
> no mysqld. If it is, try doing a shutdown and see if the load
> decreases.
>
> Sounds odd, but I have been having similar issues with MySQL.

It's not, no. It used to but it doesn't run now. The mysqldump is a  
nightly backup.

-Stut

> 2008/6/16 Stut <stuttle at gmail.com>:
>> On 16 Jun 2008, at 18:48, Oliver Fromme wrote:
>>>
>>> Stut <stuttle at gmail.com> wrote:
>>>>
>>>> I'm having a serious problem with one of my FreeBSD servers. It  
>>>> runs
>>>> FreeBSD 6.2-RELEASE, Apache 2.2.8 and PHP 5.2.1. I've checked the
>>>> hardware and it's all OK. There's approximately 400 Apache  
>>>> processes
>>>> running and a 2GB memcached instance.
>>>>
>>>> Up until last weekend this server was working perfectly at a level
>>>> of HTTP traffic higher than it's currently getting. Last week our
>>>> database server (separate server) died and had to be rebuilt. While
>>>> this was being done this server hosted the database. This has now
>>>> been completed and the PHP app is pointing back at the dedicated DB
>>>> server.
>>>>
>>>> Top shows the following...
>>>>
>>>> last pid: 26838;  load averages: 10.22, 14.06, 13.55         up
>>>> 2+00:34:47  18:03:43
>>>> 619 processes: 1 running, 618 sleeping
>>>> CPU states:  4.9% user,  0.0% nice, 24.8% system,  0.4% interrupt,
>>>> 70.0% idle
>>>> Mem: 2241M Active, 2718M Inact, 462M Wired, 394M Cache, 214M Buf,
>>>> 1747M Free
>>>> Swap: 8192M Total, 124K Used, 8192M Free
>>>>
>>>> PID    UID    THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU
>>>> COMMAND
>>>> 26807     80      1  -4    0 79892K  9996K devfs  0   0:00  2.81%
>>>> httpd
>>>> 26797     80      1  -4    0 82376K 12592K devfs  1   0:00  2.19%
>>>> httpd
>>>> 26791     80      1  -4    0 82376K 12636K devfs  0   0:00  1.85%
>>>> httpd
>>>> 26783     80      1  -4    0 82392K 12640K devfs  3   0:00  1.84%
>>>> httpd
>>>> [...]
>>>
>>> Please let "vmstat 5" run for a minute ...  Anything
>>> that looks unusual?
>>
>> procs      memory       page                    disks      
>> faults      cpu
>> r b   w avm     fre     flt  re  pi  po  fr   sr da0 pa0   in   sy   
>> cs  us
>> sy id
>> 1 412 2 8910132 2743568 2230  3   1   0 2106  93   0   0 1098 4733  
>> 3025  4
>> 17 79
>> 1 412 0 8841792 2760548 1630  0   0   0 2276   0  21   0  658 3970  
>> 6374  3
>> 26 71
>> 0 422 0 8804744 2765076 1349  0   0   0 1394   0  12   0  576 3454  
>> 5131  3
>> 26 71
>> 1 421 0 8756808 2778660 1095  0   0   0 1581   0  48   0  574 3076  
>> 4415  3
>> 25 72
>> 0 420 0 8684932 2800128 2049  0   0   0 2927   0  45   0  505 2998  
>> 3770  3
>> 24 73
>> 1 380 0 8603676 2838452 1149  0   0   0 2842   0  22   0  505 3497  
>> 4339  2
>> 26 72
>> 1 21  0 8280260 3097392 7630  0   0   0 19969  0  29   0 1241 8895  
>> 6950 10
>> 30 60
>> 1 4   0 8195828 3131992 9113  0   0   0 9742   0  78   0  996 9405  
>> 2830  7
>> 19 74
>> 0 20  0 8169288 3121688 2899  0   0   0 2098   0  47   0 1193 7740  
>> 2733  4
>> 23 73
>> 11 13  0 8123476 3128688 1947  0   0   0 2160   0  52   0 1161 6231  
>> 2617  4
>> 26 70
>> 1 14  0 8067304 3143984 2298  0   0   0 2885   0  57   0 1806 5572  
>> 3373  4
>> 25 70
>> 2 17  1 8015924 3156168 2702  0   0   0 3164   0  23   0 1384 8243  
>> 2770  6
>> 25 69
>> 1 22  0 7956476 3176376 2013  0   0   0 2879   0  23   0  917 7063  
>> 2484  6
>> 25 69
>> 0 35  0 7944760 3150452 4274  0   0   0 2806   0  21   0 1591 8281  
>> 3399  7
>> 25 68
>> 1 67  3 7903160 3158776 2043  0   0   0 2442   0  20   0 1095 6405  
>> 3605  6
>> 25 70
>> 44 69  0 7872504 3147192 2569  0   0   0 1712   0  81   0 1137 5773  
>> 4998  6
>> 26 69
>> 1 146 0 7849632 3135388 2095  0   0   0 1274   0  19   0  869 5550  
>> 5466  5
>> 26 69
>> 3 195 2 7825932 3122116 2482  0   0   0 1586   0  15   0  863 5558  
>> 6135  5
>> 26 69
>> 1 244 3 7798148 3111624 1609  0   0   0 1226   0  10   0  849 4027  
>> 6477  4
>> 27 69
>> 2 273 3 7776772 3102948 2080  0   0   0 1310   0  14   0  604 4376  
>> 6527  4
>> 26 70
>> 1 312 2 7768232 3079012 3148  0   0   0 1800   0  12   0 1066 6088  
>> 10242 6
>> 28 66
>> 1 340 0 7742680 3068244 2020  0   0   0 1421   0  74   0  729 4407  
>> 8204  4
>> 26 70
>> 2 366 0 7740324 3068068 1612  0   0   0 1553   0  11   0  613 3526  
>> 6728  3
>> 26 70
>> 1 397 1 7928688 3059900 1886  0   0   0 1344   0  12   0  515 3081  
>> 6864  3
>> 27 70
>> 1 400 0 8074560 3008988 4771  0   0   0 1457   0  14   0  950 5309  
>> 8996  5
>> 27 68
>>
>> Lots of processes blocked - which I guess is what the devfs state  
>> indicates.
>>
>>> Have you checked dmesg?
>>
>> Yes. The only odd thing I can see is the following message, but  
>> from what
>> I've read it's not critical until you get 5 and it's only in there  
>> once.
>>
>> "collecting pv entries -- suggest increasing PMAP_SHPGPERPROC|
>>
>>
>>> Is this FreeBSD i386 (32bit) or amd64 (64bit)?
>>
>> FreeBSD harold.freeads.co.uk 6.2-RELEASE FreeBSD 6.2-RELEASE #0:  
>> Fri Jan 12
>> 08:43:30 UTC 2007 root at portnoy.cse.buffalo.edu:/usr/obj/usr/src/sys/ 
>> SMP
>> amd64
>>
>>> Have you considered updating?  6.2-RELEASE isn't the
>>> freshest anymore.  You might even consider going to
>>> 7-stable and using the new ULE scheduler which copes
>>> better with SMP servers.
>>
>> I have, but I'd rather understand what's happening.
>>
>>>> As you can see there's plenty of free memory and the CPU is 70%  
>>>> idle
>>>> yet the load is sky high.
>>>
>>> Well, load 10 isn't that much for a 4-way SMP system.
>>
>> A couple of weeks ago this server was fairly fast, load never  
>> really going
>> beyond 3 and everything was reasonably responsive. Now it regularly  
>> goes up
>> to and beyond a load of 10 (more often than not at the moment) and
>> everything is slow. This means our website users are getting a very  
>> poor
>> experience which is reflected in our traffic levels which have  
>> dropped by
>> about 25% since this started happening.
>>
>> Thanks for your help. Any other ideas?
>>
>> -Stut
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