При нагрузке порядка 1500 конектов и ближе к 2 Gbps
ловлю в ps это blockdev_direct_IO
Есть варианты решения?

CenOS 6.0 2.6.32-71.29.1.el6.x86_64
RAM 16 GB
nginx 1.0.9


user web;
worker_processes 1;
worker_rlimit_nofile 32000;
error_log logs/error.log info;
events {
worker_connections 16000;
}


http {
include mime.types;
default_type application/octet-stream;

server_tokens off;

sendfile on;
tcp_nopush on;

tcp_nodelay on;
aio on;
directio 4m;
directio_alignment 4k;
output_buffers 1 1m;


keepalive_timeout 10;

client_header_timeout 20;
client_body_timeout 20;
send_timeout 20s;
resolver_timeout 0;
reset_timedout_connection on;

proxy_buffering off;

open_file_cache max=16000 inactive=10m;
open_file_cache_valid 120m;
open_file_cache_min_uses 10;
open_file_cache_errors off;