求问 available 显示还有 6.8G ，为啥 Swap 会被用光，有网上的文章说这是 swappiness 设置的问题，但是设置的 swappiness 是 30 ，6.8/15=0.43 还不到 30 了。。求解

cat /proc/sys/vm/swappiness
30

[root@localhost ~]# free -h
total used free shared buff/cache available
Mem: 15G 7.7G 182M 670M 7.6G 6.8G
Swap: 1.6G 1.6G 196K

[root@localhost ~]# cat /proc/meminfo
MemTotal: 16264392 kB
MemFree: 202556 kB
MemAvailable: 7150152 kB
Buffers: 0 kB
Cached: 7441640 kB
SwapCached: 8416 kB
Active: 10448388 kB
Inactive: 4527600 kB
Active(anon): 7025012 kB
Inactive(anon): 1195560 kB
Active(file): 3423376 kB
Inactive(file): 3332040 kB
Unevictable: 0 kB
Mlocked: 0 kB
SwapTotal: 1679356 kB
SwapFree: 244 kB
Dirty: 52 kB
Writeback: 828 kB
AnonPages: 7526168 kB
Mapped: 93996 kB
Shmem: 686224 kB
Slab: 643864 kB
SReclaimable: 530412 kB
SUnreclaim: 113452 kB
KernelStack: 25392 kB
PageTables: 79460 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 9811552 kB
Committed_AS: 15227004 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 35568 kB
VmallocChunk: 34359700252 kB
HardwareCorrupted: 0 kB
AnonHugePages: 1468416 kB
CmaTotal: 0 kB
CmaFree: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 898940 kB
DirectMap2M: 15878144 kB

[root@localhost ~]# iostat -d -x -k 1 10
Linux 3.10.0-1062.el7.x86_64 (localhost.localdomain) 2024 年 05 月 13 日 _x86_64_ (8 CPU)

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.03 0.45 3.86 8.58 179.50 182.78 58.23 0.14 9.52 36.61 26.32 14.24 17.72
dm-0 0.00 0.00 3.87 8.95 178.92 182.45 56.37 0.14 10.93 35.07 0.48 13.81 17.71
dm-1 0.00 0.00 0.02 0.08 0.06 0.32 8.00 0.25 2600.87 1909.98 2733.58 130.32 1.24

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 64.00 0.00 0.00 0.00 0.00 100.00
dm-0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 87.00 0.00 0.00 0.00 0.00 100.00
dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 64.00 0.00 0.00 0.00 0.00 100.00
dm-0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 87.00 0.00 0.00 0.00 0.00 100.00
dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 7.00 0.00 103.00 0.00 1562.00 30.33 29.70 17255.64 0.00 17255.64 8.30 85.50
dm-0 0.00 0.00 0.00 46.00 0.00 937.50 40.76 39.66 50414.85 0.00 50414.85 18.59 85.50
dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 1.00 0.00 48.00 96.00 19.43 12364.00 0.00 12364.00 1000.00 100.00
dm-0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 20.43 0.00 0.00 0.00 0.00 100.00
dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 19.00 0.00 0.00 0.00 0.00 100.00
dm-0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 20.00 0.00 0.00 0.00 0.00 100.00
dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 1.00 0.00 34.00 0.00 342.00 20.12 9.67 1767.00 0.00 1767.00 17.00 57.80
dm-0 0.00 0.00 0.00 16.00 0.00 103.50 12.94 10.20 3941.44 0.00 3941.44 36.12 57.80
dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 5.00 0.00 1548.00 619.20 0.03 5.80 0.00 5.80 2.80 1.40
dm-0 0.00 0.00 0.00 5.00 0.00 1548.00 619.20 0.03 5.80 0.00 5.80 2.80 1.40
dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
dm-0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00