RAM usada por el kernel de linux

En uno de los servidores de produccion, segun ha ido incrementandose la version del kernel:

BOOT_IMAGE=/boot/vmlinuz-3.13.0-147
Memory: 65888608K/67066776K available (7484K kernel code, 1163K rwdata, 3432K rodata, 1356K init, 1448K bss, 1178168K reserved)
BOOT_IMAGE=/boot/vmlinuz-4.4.0-131
Memory: 65862872K/67066776K available (8546K kernel code, 1313K rwdata, 4000K rodata, 1516K init, 1316K bss, 1203904K reserved, 0K cma-reserved)
BOOT_IMAGE=/boot/vmlinuz-4.15.0-29-generic
Memory: 65843760K/67066776K available (12300K kernel code, 2470K rwdata, 4240K rodata, 2408K init, 2416K bss, 1223016K reserved, 0K cma-reserved)
slabtop: 1254166,96K / 1292164,51K (97,1%)
3>cache: 202295,65K / 293943,45K (68,8%)
smem -twk Used Cache Noncache
kernel dynamic memory 1.1G 595.0M 489.7M
userspace memory 1.0G 364.2M 699.5M
echo 3 > /proc/sys/vm/drop_caches
kernel dynamic memory 613.6M 130.0M 483.6M

En un webserver casero

BOOT_IMAGE=/boot/vmlinuz-3.13.0-93-generic
Memory: 421788K/457104K available (6579K kernel code, 646K rwdata, 2776K rodata, 884K init, 924K bss, 35316K reserved, 0K highmem)
slabtop: 24514,04K / 27976,49K (87,6%)
smem -twk
kernel dynamic memory 218.5M 154.3M 64.1M
userspace memory 180.3M 61.8M 118.5M
echo 3 > /proc/sys/vm/drop_caches
kernel dynamic memory 86.5M 22.0M 64.4M

En la maquina de desktop

BOOT_IMAGE=/boot/vmlinuz-4.12.14-lp150.12.48-default
Memory: 5782456K/8382856K available (10256K kernel code, 1434K rwdata, 3340K rodata, 2052K init, 9908K bss, 242448K reserved, 0K cma-reserved)
slabtop 81806.00K / 114815.17K (71.3%)