Как улучшить производительность Лака?

Мы испытываем странную проблему с нашей текущей конфигурацией Лака.

4x веб-серверы (IIS 6.5 в Windows 2003 Server, каждый установленный на Intel(R) Xeon(R) CPU E5450 3.00 ГГц Четырехъядерного, 4 ГБ RAM)

3x Серверы Лака (лакируют 3.0.3 пересмотра 9e6a70f на Ubuntu 12.04.2 LTS - 64 разрядных/точных, Ядро 3.2.0-29-универсальный Linux, каждый установленный на Intel(R) Xeon(R) CPU E5450 3.00 ГГц Четырехъядерного, 4 ГБ RAM),

Производительность Серверов Лака ужасно плоха в целом, до такой степени, что, если мы закрываем одного из них, другие два не могут обработать все запросы и начать пропускать удары, приводящие к незаконченным запросам, тайм-аутам, 404, и т.д.

Что мы можем сделать для улучшения нашей производительности Лака? Полагание, что мы получаем меньше, чем запрос 5k в секунды во время нашего макс. пика, мы должны смочь служить нашим страницам даже с единственным из них без любой проблемы.

Мы используем стандарт, ванильный CFG, как показано этим varnishadm> param.show вывод:

acceptor_sleep_decay        0.900000 []
acceptor_sleep_incr         0.001000 [s]
acceptor_sleep_max          0.050000 [s]
auto_restart                on [bool]
ban_dups                    on [bool]
ban_lurker_sleep            0.010000 [s]
between_bytes_timeout       60.000000 [s]
cc_command                  "exec gcc -std=gnu99 -g -O2 -pthread -fpic -shared -                                                                                                                               Wl,-x -o %o %s"
cli_buffer                  8192 [bytes]
cli_timeout                 20 [seconds]
clock_skew                  10 [s]
connect_timeout             0.700000 [s]
critbit_cooloff             180.000000 [s]
default_grace               10.000000 [seconds]
default_keep                0.000000 [seconds]
default_ttl                 120.000000 [seconds]
diag_bitmap                 0x0 [bitmap]
esi_syntax                  0 [bitmap]
expiry_sleep                1.000000 [seconds]
fetch_chunksize             128 [kilobytes]
fetch_maxchunksize          262144 [kilobytes]
first_byte_timeout          60.000000 [s]
group                       varnish (113)
gzip_level                  6 []
gzip_memlevel               8 []
gzip_stack_buffer           32768 [Bytes]
gzip_tmp_space              0 []
gzip_window                 15 []
http_gzip_support           off [bool]
http_max_hdr                64 [header lines]
http_range_support          on [bool]
http_req_hdr_len            8192 [bytes]
http_req_size               32768 [bytes]
http_resp_hdr_len           8192 [bytes]
http_resp_size              32768 [bytes]
idle_send_timeout           60 [seconds]
listen_address              :80
listen_depth                1024 [connections]
log_hashstring              on [bool]
log_local_address           off [bool]
lru_interval                2 [seconds]
max_esi_depth               5 [levels]
max_restarts                4 [restarts]
nuke_limit                  50 [allocations]
pcre_match_limit            10000 []
pcre_match_limit_recursion  10000 []
ping_interval               3 [seconds]
pipe_timeout                60 [seconds]
prefer_ipv6                 off [bool]
queue_max                   100 [%]
rush_exponent               3 [requests per request]
saintmode_threshold         10 [objects]
send_timeout                600 [seconds]
sess_timeout                5 [seconds]
sess_workspace              16384 [bytes]
session_linger              50 [ms]
session_max                 100000 [sessions]
shm_reclen                  255 [bytes]
shm_workspace               8192 [bytes]
shortlived                  10.000000 [s]
syslog_cli_traffic          on [bool]
thread_pool_add_delay       2 [milliseconds]
thread_pool_add_threshold   2 [requests]
thread_pool_fail_delay      200 [milliseconds]
thread_pool_max             2000 [threads]
thread_pool_min             5 [threads]
thread_pool_purge_delay     1000 [milliseconds]
thread_pool_stack           unlimited [bytes]
thread_pool_timeout         300 [seconds]
thread_pool_workspace       65536 [bytes]
thread_pools                2 [pools]
thread_stats_rate           10 [requests]
user                        varnish (106)
vcc_err_unref               on [bool]
vcl_dir                     /etc/varnish
vcl_trace                   off [bool]
vmod_dir                    /usr/lib/varnish/vmods
waiter                      default (epoll, poll)

Это - наш default.vcl файл: ССЫЛКА

sub vcl_recv {

        # BASIC recv COMMANDS:
        #
        # lookup -> search the item in the cache
        # pass -> always serve a fresh item (no-caching)
        # pipe -> like pass but ensures a direct-connection with the backend (no-cache AND no-proxy)

        # Allow the backend to serve up stale content if it is responding slow.
        # This defines when Varnish should use a stale object if it has one in the cache.
        set req.grace = 30s;

        if (client.ip == "127.0.0.1") {
                # request from NGINX - do not alter X-Forwarded-For
                set req.http.HTTPS = "on";
        }
        else {
                # Add an X-Forwarded-For to keep track of original request
                unset req.http.HTTPS;
                unset req.http.X-Forwarded-For;
                set req.http.X-Forwarded-For = client.ip;
        }
        set req.backend = www_director;

        # Strip all cookies to force an anonymous request when the back-end servers are down.

        if (!req.backend.healthy) {
          unset req.http.Cookie;
        }

        ## HHTP Accept-Encoding
        if (req.http.Accept-Encoding) {
                if (req.http.Accept-Encoding ~ "gzip") {
                        set req.http.Accept-Encoding = "gzip";
                }
                else if (req.http.Accept-Encoding ~ "deflate") {
                        set req.http.Accept-Encoding = "deflate";
                }
                else {
                        unset req.http.Accept-Encoding;
                }
        }

        if (req.request != "GET" &&
            req.request != "HEAD" &&
            req.request != "PUT" &&
            req.request != "POST" &&
            req.request != "TRACE" &&
            req.request != "OPTIONS" &&
            req.request != "DELETE") {
            /* non-RFC2616 or CONNECT */
               return (pipe);
        }

        if (req.request != "GET" && req.request != "HEAD") {
          /* only deal with GET and HEAD by default */
          return (pass);
        }

        if (req.http.Authorization) {
          return (pass);
        }

        if (req.http.HTTPS ~ "on") {
          return (pass);
        }


######################################################
# COOKIE HANDLING
######################################################

# METHOD 1: do not remove cookies, but pass the page if they contain TB_NC

        if (!(req.url ~ "(?i)\.(png|gif|ipeg|jpg|ico|swf|css|js)(\?[a-z0-9]+)?$")) {
                if (req.http.Cookie && req.http.Cookie ~ "TB_NC") {
                        return (pass);
                }
        }
        return (lookup);
}


# Code determining what to do when serving items from the IIS Server

sub vcl_fetch {
        unset beresp.http.Server;
        set beresp.http.Server = "Server-1";
  # Allow items to be stale if needed. This is the maximum time Varnish should keep an object.
  set beresp.grace = 1h;

  if (req.url ~ "(?i)\.(png|gif|ipeg|jpg|ico|swf|css|js)(\?[a-z0-9]+)?$") {
     unset beresp.http.set-cookie;
  }

  # Default Varnish VCL logic
  if (!beresp.cacheable ||
        beresp.ttl <= 0s ||
        beresp.http.Set-Cookie ||
        beresp.http.Vary == "*") {
      set beresp.ttl = 120 s;
      return(hit_for_pass);
  }

  # Not Cacheable if it has specific TB_NC no-caching cookie
  if (req.http.Cookie && req.http.Cookie ~ "TB_NC") {
    set beresp.http.X-Cacheable = "NO:Got Cookie";
    set beresp.ttl = 120 s;
    return(hit_for_pass);
  }

  # Not Cacheable if it has Cache-Control private
  else if (beresp.http.Cache-Control ~ "private") {
    set beresp.http.X-Cacheable = "NO:Cache-Control=private";
    set beresp.ttl = 120 s;
    return(hit_for_pass);
  }

  # Not Cacheable if it has Cache-Control no-cache or Pragma no-cache
  else if (beresp.http.Cache-Control ~ "no-cache" || beresp.http.Pragma ~ "no-cache") {
    set beresp.http.X-Cacheable = "NO:Cache-Control=no-cache (or pragma no-cache)";
    set beresp.ttl = 120 s;
    return(hit_for_pass);
  }

  # If we reach to this point, the object is cacheable.

  # Cacheable but with not enough ttl: we need to extend the lifetime of the object artificially
  # NOTE: Varnish default TTL is set in /etc/sysconfig/varnish
  #       and can be checked using the following command:
  #       varnishadm param.show default_ttl

  else if (beresp.ttl < 1s) {
    set beresp.ttl   = 5s;
    set beresp.grace = 5s;
    set beresp.http.X-Cacheable = "YES:FORCED";
  }

  # Cacheable and with valid TTL.
  else {
    set beresp.http.X-Cacheable = "YES";
  }

# DEBUG INFO (Cookies)
# set beresp.http.X-Cookie-Debug = "Request cookie: " + req.http.Cookie;
  return(deliver);
}

sub vcl_error {
    set obj.http.Content-Type = "text/html; charset=utf-8";
    if (obj.status == 404) {
        synthetic {"
            <!-- Markup for the 404 page goes here -->
        "};
    }
    else if (obj.status == 500) {
        synthetic {"
            <!-- Markup for the 500 page goes here -->
        "};
    }
    else if (obj.status == 503) {
      if (req.restarts < 4) { return(restart); }
      else {
         synthetic {"
             <!-- Markup for the 503 page goes here -->
         "};
      }
    }
    else {
        synthetic {"
            <!-- Markup for a generic error page goes here -->
        "};
    }
}

sub vcl_deliver {
    if (obj.hits > 0) {
      set resp.http.X-Cache = "HIT";
    } else {
      set resp.http.X-Cache = "MISS";
    }
}

Заранее спасибо,