Shared memory page size and huge pages with mysql

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Hello all,

I would like to discuss with you about an issue related the use of the huge pages on a redhat system and mysql.
I configured about 50Gb of huge pages for mysql, then I started the mysql instance.

What I see from ipcs -m command is:

------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x00000000 455770112 mysql 600 138412032 1 dest
0x00000000 455802881 mysql 600 138412032 1 dest
0x00000000 455835650 mysql 600 138412032 1 dest
0x00000000 455868419 mysql 600 138412032 1 dest
0x00000000 455901188 mysql 600 138412032 1 dest
0x00000000 455933957 mysql 600 138412032 1 dest
0x00000000 455966726 mysql 600
.....
....
....
and further 400 lines

xxxx: # ipcs -m |wc -l
420 <===

The size of the shared segment is 138412032 bytes , thus I got 420 shared segment of 138412032 bytes.

The questions are:
1) How can I increase the size of shared segment? How to control the size of the shared segment?
2) Could I get perforamance issue managing 420 shared segment?
Should be better to better to manage less shared segemnt?

sysctl -a |grep shm
kernel.shm_next_id = -1
kernel.shm_rmid_forced = 0
kernel.shmall = 1073741824
kernel.shmmax = 68719476736
kernel.shmmni = 4096
vm.hugetlb_shm_group = 478

thank you
Adriano

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