如何释放android系统中pss cache住的内存

Question

通过dumpsys meminfo可以统计查看到android各进程内存使用情况：

Total RAM: 463136 kB
Free RAM: 170277 kB (48221 cached pss + 68780 cached + 53276 free)
Used RAM: 173253 kB (152085 used pss + 3160 buffers + 176 shmem + 17832 slab)
Lost RAM: 119606 kB
ZRAM: 2168 kB physical used for 2836 kB in swap (51196 kB total swap)
KSM: 4940 kB saved from shared 36 kB
6280 kB unshared; 84220 kB volatile
Tuning: 48 (large 128), oom 108462 kB, restore limit 36154 kB (low-ram)

在这Free RAM中的pss cached内存是否可以被释放？要如何释放？