[SERVER-16263] high page default Created: 21/Nov/14  Updated: 24/Jan/15  Resolved: 23/Jan/15

Status: Closed
Project: Core Server
Component/s: Performance
Affects Version/s: 2.4.8
Fix Version/s: None

Type: Question Priority: Major - P3
Reporter: qing cao Assignee: Unassigned
Resolution: Incomplete Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Participants:

 Description   

Hi,
I have a problem.The mongodb server is a machine with 32G of memory,but recently the use of resident memory is small less than 8G.This problem causes high page default.
But on the server no other process consumes memory.I am confused.

The output of some informations about the os and process:

[root@dal05mgo05 ~]# free -m
             total       used       free     shared    buffers     cached
Mem:         32073      31880        193          0         26      30642
-/+ buffers/cache:       1212      30861
Swap:         4095          0       4095
 
[root@dal05mgo05 ~]# cat /proc/meminfo |egrep -i mapped
Mapped:          7100988 kB
 
[root@dal05mgo05 ~]# mongostat -ucaoqing -p
connected to: 127.0.0.1
Enter password: 
insert  query update delete getmore command flushes mapped  vsize    res faults  locked db idx miss %     qr|qw   ar|aw  netIn netOut  conn     set repl       time 
     1     74     11     *0      33    43|0       0   231g   463g  8.03g    779 PCMDB:0.0%          0       0|0     8|0    54k    33m   152 rs_main  PRI   04:36:02 
    *0     85     16     *0      44    25|0       0   231g   463g  7.96g    848 PCMDB:0.9%          0       5|0     8|1    52k    25m   152 rs_main  PRI   04:36:03 
     1     98     20     *0      51    32|0       0   231g   463g  8.01g    571 PCMDB:2.0%          0       0|0     8|0    76k    25m   153 rs_main  PRI   04:36:04 
    *0    106     24     *0      68    41|0       0   231g   463g  8.02g    572 PCMDB:3.1%          0       0|0     8|0    88k    25m   152 rs_main  PRI   04:36:05 
     2     78     23     *0      70    43|0       0   231g   463g   8.1g    677 PCMDB:1.3%          0       2|0     8|1    84k    25m   152 rs_main  PRI   04:36:06 
    *0     72     11     *0      33    29|0       0   231g   463g  8.11g    572 PCMDB:3.1%          0      17|0     9|0    43k    33m   152 rs_main  PRI   04:36:07 
	
	
[root@dal05mgo05 ~]# top
top - 04:38:51 up 374 days,  4:03,  4 users,  load average: 7.99, 10.88, 10.03
Tasks: 576 total,   1 running, 575 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.6%us,  0.3%sy,  0.0%ni, 92.3%id,  5.7%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:  32843352k total, 32636324k used,   207028k free,    31612k buffers
Swap:  4194296k total,        0k used,  4194296k free, 31375100k cached
 
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND                                                                                         
13425 mongod    20   0  463g 6.8g 6.6g S 59.3 21.7  71:08.37 mongod                                                                                          
  467 root      39  19     0    0    0 S  1.0  0.0   5748:27 kipmi0                                                                                          
25647 root      20   0 19692 1764 1032 R  0.7  0.0   0:00.07 top                                                                                             
  354 root      20   0     0    0    0 S  0.3  0.0 227:24.17 kswapd0                                                                                         
  355 root      20   0     0    0    0 S  0.3  0.0 228:56.67 kswapd1                                                                                         
 2380 root      20   0     0    0    0 S  0.3  0.0 264:08.46 jbd2/sda5



 Comments   
Comment by Ramon Fernandez Marina [ 05/Dec/14 ]

caoqing, we haven't heard back from you for a while. Have you had a chance to follow up on Eliot's comment and see if the situation improves?

Comment by Eliot Horowitz (Inactive) [ 23/Nov/14 ]

You should check the read ahead seetings on the drive, that's the most likely cause.

take a look at the readahead section on http://docs.mongodb.org/manual/administration/production-notes/

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