Kernel.shmall和kernel.shmmax

if any of the current values are larger than the recommended value, then specify the larger value.

If the current value for any parameter is higher than the value listed in this table, then do not change the value of that parameter

如果/etc/sysctl.conf中的kernel.shmmax比推荐的值大 那么使用较大的值

[oracle@jssweb ~]$ getconf PAGE_SIZE 查看页大小

#

kernel.shmall = 2097152 则一共是8G的共享内存总量

SHMALL 单位页

Finally, we look at the SHMALL shared memory kernel parameter. This parameter controls the total amount of shared memory (in pages) that can be used at one time on the system. In short, the value

of this parameter should always be at least:
ceil(SHMMAX/PAGE_SIZE)

Kernel.shmall：共享内存总量，以页为单位。Linux 共享内存页大小为4K