Mysql CPU high, Need help to Optimize

[Tinh Duong]

I have a server with these specs :

Last login: Fri Aug 24 13:26:37 2012 from 118.71.57.107
[root@localhost ~]# free
             total       used       free     shared    buffers     cached
Mem:       4149456    2817900    1331556          0     342292    1348472
-/+ buffers/cache:    1127136    3022320
Swap:      8193140      55532    8137608
[root@localhost ~]# cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 15
model name      : Intel(R) Xeon(R) CPU           X3210  @ 2.13GHz
stepping        : 11
cpu MHz         : 2128.000
cache size      : 4096 KB
physical id     : 0
siblings        : 4
core id         : 0
cpu cores       : 4
apicid          : 0
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni
 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm
bogomips        : 4256.15

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 6
model           : 15
model name      : Intel(R) Xeon(R) CPU           X3210  @ 2.13GHz
stepping        : 11
cpu MHz         : 2128.000
cache size      : 4096 KB
physical id     : 0
siblings        : 4
core id         : 1
cpu cores       : 4
apicid          : 1
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni
 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm
bogomips        : 4255.40

processor       : 2
vendor_id       : GenuineIntel
cpu family      : 6
model           : 15
model name      : Intel(R) Xeon(R) CPU           X3210  @ 2.13GHz
stepping        : 11
cpu MHz         : 2128.000
cache size      : 4096 KB
physical id     : 0
siblings        : 4
core id         : 2
cpu cores       : 4
apicid          : 2
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni
 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm
bogomips        : 4255.43

processor       : 3
vendor_id       : GenuineIntel
cpu family      : 6
model           : 15
model name      : Intel(R) Xeon(R) CPU           X3210  @ 2.13GHz
stepping        : 11
cpu MHz         : 2128.000
cache size      : 4096 KB
physical id     : 0
siblings        : 4
core id         : 3
cpu cores       : 4
apicid          : 3
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 10
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni
 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr lahf_lm
bogomips        : 4255.43

[root@localhost ~]# cat /proc/meminfo
MemTotal:      4149456 kB
MemFree:       1149436 kB
Buffers:        346228 kB
Cached:        1366152 kB
SwapCached:      12812 kB
Active:        2122160 kB
Inactive:       596420 kB
HighTotal:     3274156 kB
HighFree:       886504 kB
LowTotal:       875300 kB
LowFree:        262932 kB
SwapTotal:     8193140 kB
SwapFree:      8137608 kB
Dirty:           12064 kB
Writeback:           0 kB
AnonPages:     1003532 kB
Mapped:          21916 kB
Slab:           253876 kB
PageTables:      13496 kB
NFS_Unstable:        0 kB
Bounce:              0 kB
CommitLimit:  10267868 kB
Committed_AS:  3965640 kB
VmallocTotal:   116728 kB
VmallocUsed:      7508 kB
VmallocChunk:   108592 kB
HugePages_Total:     0
HugePages_Free:      0
HugePages_Rsvd:      0
Hugepagesize:     2048 kB
[root@localhost ~]#

Sometimes, the CPU used by mysql increase to 100~150, maybe 200, this time, website load very slowly.
When it return to <100, everything seems to be ok.

So, Please help me to tunning my config.
This is my.cnf :

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
# skip-networking
skip-name-resolve
skip-external-locking
# Disabling symbolic-links is recommended to prevent assorted security risks
# symbolic-links=0

max_connections=300
max_user_connections =0

log_slow_queries = /var/log/mysql/mysql-slow.log
long_query_time = 2

query_cache_size = 16M
join_buffer_size = 4M
tmp_table_size = 64M


query-cache-type = 1
key_buffer = 128M
key_buffer_size = 128M
max_allowed_packet = 32M
sort_buffer_size = 2M
read_buffer_size = 2M
read_rnd_buffer_size = 8M
myisam_sort_buffer_size = 64M
thread_cache = 16
query_cache_type = 1
query_cache_size = 128M
query_cache_limit = 148M
thread_cache_size=16K
max_heap_table_size = 64M
table_cache = 1K
table_definition_cache = 4K
open_files_limit = 3K
table_open_cache = 96
thread_concurrency = 6

wait_timeout=20



[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
nice = -5