More CPU Usage

[Srinivas Pokala]

HI
I am getting more cpu usage at heavy traffic.

Online users 600 requests per sec
Max. concurrent connections 2400
Almost 8000 select queries per seconds

Configuration values:

innodb buffer pool size: 85GB
thread_cache_size=500;
read_buffer_size=6291456;
max_connections=2500;
innodb_print_all_deadlocks=ON;
innodb_io_capacity=1000;
innodb_lru_scan_depth=100;
innodb_flush_neighbors=2;
innodb_max_dirty_pages_pct_lwm=1;
innodb_max_dirty_pages_pct=1;
innodb_change_buffer_max_size=50;
sort_buffer_size=8388608;
range_optimizer_max_mem_size=16777216;
innodb_flush_log_at_trx_commit=2;
key_cache_age_threshold=7200;
key_cache_block_size=16384;
key_cache_division_limit=50;
join_buffer_size=3145728;
table_open_cache=9216;
binlog_expire_logs_seconds=259200;
log_queries_not_using_indexes=OFF;
slow_query_log =OFF;
key_buffer_size=268435456;
log_error_verbosity=1;
read_rnd_buffer_size=1048576;

Whatever queries we are using with index and joins executed in 0.005 seconds maximum, but the same queries take over 20 seconds when more users are online.

Please suggest to need any changes in MySQL values

Thanks
Srinivas