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What is the filemon "swapper" process on AIX 7.1

Posted on 2013-11-13
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Last Modified: 2013-11-13
Hi !

I'm trying to understand what's this "swapper" process shown on filemon results. I see a high access to "unix" and "utmp" files, and I suspect it's linked to this swap. Somehow we may be reaching a limit forcing a swap, although there's no disk swap as shown by lsps.

Filemon results (90 seconds):

Most Active Files
------------------------------------------------------------------------
  #MBs  #opns   #rds   #wrs  file                     volume:inode
------------------------------------------------------------------------
  21.5     71   5507      0  unix                     /dev/hd2:14297
  15.6   4197   9288      0  UV.ACCOUNT               /dev/lvmvb1:4417
  13.4    101   3600      0  GVMTA01A                 /dev/lvmvdmn1:333975
  12.2     75   8609      0  GVMTA315
  10.6     13    938      0  INDEX.008                /dev/lvmvi3:8246
  10.2     38   5483      0  GVMTA011                 /dev/lvmvdrt1:88996
   9.1      5   1360    400  INDEX.MAP                /dev/lvmvima1:106962
   8.9     13    965    185  INDEX.000                /dev/lvmvi2:73761
   8.4    633   1715      0  CONTROLE                 /dev/lvmvdmn1:1619
   8.1     56  13162      0  utmp                     /dev/hd4:17195
   7.6     13   3906      0  INDEX.013                /dev/lvmvi3:20494
   7.6    192   1959      0  CONTROLE
   7.1     12    468      0  INDEX.009                /dev/lvmvi3:8247
   6.0    120   1479      0  INDEX.000                /dev/lvmvi3:61445
   5.9      9    388      0  INDEX.018                /dev/lvmvi3:8261
   5.7     18    746      0  INDEX.005                /dev/lvmvi2:8205
   5.4     35   1446      0  GVMTA01A
   4.9    257   1929      0  INDEX.000                /dev/lvmvi2:36884
   4.6   2965   6213      0  VOC                      /dev/lvmvdmn1:2141
   4.6     32    608      0  INDEX.007                /dev/lvmvitm1:118793
......

Most Active Files Process-Wise
------------------------------------------------------------------------
  #MBs  #opns   #rds   #wrs  file                     PID(Process:TID)
------------------------------------------------------------------------
   0.6      2    868      0  VOC                     0(swapper:113378053)
   0.5      1    125      0  unix                    0(swapper:38273875)
   0.4      1    107      0  unix                    0(swapper:84476297)
   0.4      1    671      0  utmp                    0(swapper:114820257)
   0.4      1    663      0  utmp                    0(swapper:24118315)
   0.4      3    480      0  group                   0(swapper:63833811)
   0.4      1     95      0  unix                    0(swapper:6161987)
   0.4      1     95      0  unix                    0(swapper:113378085)
   0.4      1     94      0  unix                    0(swapper:88999569)
   0.4      1     94      0  unix                    0(swapper:88999565)
   0.4      1     94      0  unix                    0(swapper:38340651)
   0.4      1     94      0  unix                    0(swapper:75694553)
   0.4      1     94      0  unix                    0(swapper:49808137)
   0.4      1     94      0  unix                    0(swapper:8782793)
   0.4      1     94      0  unix                    0(swapper:329169)
   0.4      1     94      0  unix                    0(swapper:8782763)
   0.4      1     94      0  unix                    0(swapper:35127801)
   0.4      1     94      0  unix                    0(swapper:41813585)
   0.4      1     94      0  unix                    0(swapper:113509137)
   0.4      1     94      0  unix                    0(swapper:116131205)
   0.4      1     94      0  unix                    0(swapper:6161995)
   0.4      1     94      0  unix                    0(swapper:8586103)
   0.4      1     94      0  unix                    0(swapper:26805461)
   0.4      1     94      0  unix                    0(swapper:105711125)
   0.4      1     94      0  unix                    0(swapper:116785483)
   0.4      1     94      0  unix                    0(swapper:26936327)
   0.4      1     94      0  unix                    0(swapper:48236639)
   0.4      1     94      0  unix                    0(swapper:29427077)
   0.4      1     94      0  unix                    0(swapper:108659519)
   0.4      1     94      0  unix                    0(swapper:108659511)
   0.4      1     94      0  unix                    0(swapper:18875507)
   0.4      1     94      0  unix                    0(swapper:113378105)
   0.4      1     94      0  unix                    0(swapper:87426203)
   0.4      1     94      0  unix                    0(swapper:39912431)
   0.4      1     94      0  unix                    0(swapper:94242335)
   0.4      1     94      0  unix                    0(swapper:117048265)
   0.4      1     94      0  unix                    0(swapper:63112021)
   0.4      1     94      0  unix                    0(swapper:128451783)
   0.4      1     94      0  unix                    0(swapper:6164073)
   0.4      1     94      0  unix                    0(swapper:33293495)
   0.4      1    594      0  utmp                    0(swapper:103219639)
   0.4      1    587      0                          0(swapper:1967415)
   0.4      1    565      0  telnetd.cat             0(swapper:86704501)


[root@p750 integral]# lsps -a
Page Space      Physical Volume   Volume Group Size %Used Active  Auto  Type Chksum
hd6             hdisk0            rootvg       33280MB     1   yes   yes    lv     0

[root@p750 integral]# uptime
  06:25PM   up 18 days,  12:13,  1618 users,  load average: 17.44, 20.59, 20.12

This is a p750, 96GB RAM, 16 Quad core CPUs.

Thanks in advance,

Ronald
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Comment
Question by:rsekkel
2 Comments
 
LVL 68

Accepted Solution

by:
woolmilkporc earned 500 total points
ID: 39646231
Hi,

the (now misleading) name "swapper" comes from the old "swap" mechanism where all the memory pages of processes were swapped out to make room for new processes.

Nowadays "swapper" is responsible for "harvesting" zombie processes, in cooperation with the "reaper" process, and for other process scheduling and memory allocation tasks.
Under Linux this process is called "sched", by the way.

PID 0 is initially a pre-init process to load the boot image into memory and perform system initialization. Later on, PID 0 is simply reused for the said "swapper".

"unix" is the AIX kernel on disk. The swapper has to access it rather often in order to read back in kernel pages which have been overlaid by other kernel pages.
This mechanism is not quite transparent, and IBM don't publish much info abour it.

Anyway, "swapper" has (almost) nothing to do with paging, so it's no wonder that you don't see any paging space consumption despite of "swapper's" apparent activity.

wmp
0
 

Author Closing Comment

by:rsekkel
ID: 39646379
Hi wmp !

Thanks for your quick response.
I could not find anything about this new "swapper".
Thanks a lot.

Ron
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