리눅스 시스템 스왑 메모리 확인

스왑메모리 체크 방법 3가지

[darksharavim]free -h
              total        used        free      shared  buff/cache   available
Mem:            15G        7.4G        4.3G        219M        3.8G        7.5G
Swap:          5.0G        1.0G        4.0G

1. /proc/[pid]/smaps

[darksharavim]cat /proc/29771/smaps  | more
00400000-01028000 r-xp 00000000 fd:00 105860612                          /apps/php7/sbin/php-fpm (deleted)
Size:              12448 kB
Rss:                   0 kB
Pss:                   0 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:         0 kB
Referenced:            0 kB
Anonymous:             0 kB
AnonHugePages:         0 kB
Swap:                  0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB
Locked:                0 kB
VmFlags: rd ex mr mp me dw sd

2. /proc/[pid]/status

[darksharavim]cat /proc/29771/status
Name:	php-fpm
Umask:	0022
State:	S (sleeping)
Tgid:	29771
Ngid:	0
Pid:	29771
PPid:	29770
TracerPid:	0
Uid:	99	99	99	99
Gid:	99	99	99	99
FDSize:	64
Groups:	99 
VmPeak:	  222268 kB
VmSize:	  222220 kB
VmLck:	       0 kB
VmPin:	       0 kB
VmHWM:	    4292 kB
VmRSS:	     268 kB
RssAnon:	       0 kB
RssFile:	     264 kB
RssShmem:	       4 kB
VmData:	    5412 kB
VmStk:	     132 kB
VmExe:	   12448 kB
VmLib:	   15148 kB
VmPTE:	     228 kB
VmSwap:	    3356 kB
Threads:	1
SigQ:	0/63448
SigPnd:	0000000000000000
ShdPnd:	0000000000000000
SigBlk:	0000000000000000
SigIgn:	0000000000001000
SigCgt:	0000000180000004
CapInh:	0000000000000000
CapPrm:	0000000000000000
CapEff:	0000000000000000
CapBnd:	0000001fffffffff
CapAmb:	0000000000000000
NoNewPrivs:	0
Seccomp:	0
Speculation_Store_Bypass:	vulnerable
Cpus_allowed:	f
Cpus_allowed_list:	0-3
Mems_allowed:	00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000001
Mems_allowed_list:	0
voluntary_ctxt_switches:	1
nonvoluntary_ctxt_switches:	0

3. smem command

위 1, 2방법은 문제가 pid를 알아야만 확인 가능하지만 smem을 이용하면 좀더 쉽게 확인가능.

[darksharavim]yum -y install smem

[darksharavim]smem -t | head -10
  PID User     Command                         Swap      USS      PSS      RSS 
29771 nobody   php-fpm: pool www               3356        4        9      472 
29772 nobody   php-fpm: pool www               3356        4        9      472 
  684 root     /sbin/agetty --noclear tty1      128        4       13      684 
24353 root     cat                               72       28       35      528 
24354 root     cat                               72       32       39      532 
  666 root     /usr/bin/VGAuthService -s       1436       36       53     1020 
13304 root     cat                                0       92       99      592 
24971 root     cat                                0       96      100      568 
25983 root     cat                                0       96      100      568

vm.swappiness

리눅스 커널 속성 중 하나
스왑메모리 활용 수준 조절
스왑 사용의 적극성 수준

값의 범위: 0 ~ 100 (기본값: 60)

value	discription
vm.swappiness = 0	스왑 사용안함
vm.swappiness = 1	스왑 사용 최소화
vm.swappiness = 60	기본값
vm.swappiness = 100	적극적으로 스왑 사용

 

# 즉시반영(일시적)
[root@zetawiki ~]# sysctl vm.swappiness=40
vm.swappiness = 40

[root@zetawiki ~]# sysctl -w vm.swappiness=40
vm.swappiness = 40

[root@zetawiki ~]# echo 40 > /proc/sys/vm/swappiness
[root@zetawiki ~]# sysctl vm.swappiness
vm.swappiness = 40

# 영구적욜
vi /etc/sysctl.conf
vm.swappiness = 40

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3. swap 메모리 충격 완충제