<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Hello,</div><div><br></div><div>... and use kernel poll. </div><div>Put flag +K true to vm.<br><br>Best Regards,<div>Dmitry >-|-|-*></div><div><br></div></div><div><br>On 20.5.2013, at 18.28, Arun Muralidharan <<a href="mailto:arun11299@gmail.com">arun11299@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr"><font face="courier new, monospace">Hello Niean,<br></font><div style=""><font face="courier new, monospace">Mentioned below are few of my suggestions:</font></div><div style=""><font face="courier new, monospace">1) Disable Nagle in server.</font></div>
<div style=""><font face="courier new, monospace">2) Try to use {active, once} in server. {active, true} setting may overflow your TCP buffer. In between, how much have you set the TCP read-write buffer (both in OS and application)?</font></div>
<div style=""><font face="courier new, monospace">3) Not sure what you are trying to achieve with port_command. Its not clear to me..</font></div><div style=""><font face="courier new, monospace"><br></font></div><div style=""><font face="courier new, monospace">Other design related suggestions would be to:</font></div>
<div style=""><font face="courier new, monospace">1) Use async communication model using prim_inets as the listener.</font></div><div style=""><font face="courier new, monospace">2) Better to use an FSM for managing socket states and flow control.</font></div>
<div style=""><font face="courier new, monospace"><br></font></div><div style=""><font face="courier new, monospace">Thanks,</font></div><div style=""><font face="courier new, monospace">Arun</font></div></div><div class="gmail_extra">
<br clear="all"><div>-Arun</div>
<br><br><div class="gmail_quote">On Mon, May 20, 2013 at 8:00 PM, 聂安 <span dir="ltr"><<a href="mailto:nieanan3602@163.com" target="_blank">nieanan3602@163.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="line-height:1.7;font-size:14px;font-family:arial"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;line-height:normal">hi all,<div>I have a question about the high cpu usage when sending and receiving data via erlang-socket. </div>
<div>My program uses a C/S mode. First, the server start a listening socket, and then the client connect to the server by using gen_tcp:connect. When establishing a connection, the client will keep sending "info" package to the server while waiting for a response from the client ; the server will respond an "info_ack" to the client when receiving a "info" package. When there's one client, at most 20000 packages per second are sent betweent C/S, while cpu usage reaches about 90%. My package is very little, at most 10Bytes, so my netcard is idle. When doing the same thing by C language, the cpu usage is just 6% while my netcard turns busy with about 500000 packa
ges per second. <br></div><div>I have no idea why erlang gets so cpu-consuming. My program goes as follows:</div><div><br></div><div>Server</div><div>config items about socket setting:</div><div>{tcp_listen_opts, [<span><font color="#00ff00" size="4">binary,{packet,0},{reuseaddr,<u></u>true},{exit_on_close,true},{<u></u>active,false}<u></u><u></u></font></span>]}<br>
</div><div><br></div><div><div> 30 start_connection(Parent, Sock, SockTransform) -></div><div> 31 process_flag(trap_exit, true),</div><div> 32 Name =</div><div> 33 case catch ?NET:connection_string(Sock, inbound) of</div>
<div> 34 {ok, Str} -> Str;</div><div> 35 {error, enotcon} -> ?NET:fast_close(Sock),exit(<u></u>normal);<u></u></div><div> 36 {error, _Reason} -> ?NET:fast_clost(Sock),exit(<u></u>normal)<u></u></div>
<div> 37 end,</div><div>
38 Msg = io_lib:format("accept connection ~p(~p)", [Name, self()]),</div><div> 39 ?DEBUG(Msg), log:log(notice, ?MODULE, Msg),</div><div> 40 ClientSock = socket_op(Sock, SockTransform),</div><div> 41 ClientSock = Sock,</div>
<div> 42 {PHost, PPort, Host, Port} =</div><div> 43 socket_op(Sock, fun(S)->?NET:socket_ends(S,<u></u>inbound) end),<u></u></div><div> 44 State = #state{</div><div> 45 parent = Parent,</div>
<div> 46 sock = ClientSock,</div><div> 47 name = list_to_binary(Name),</div><div> 48 callback = undefined,</div><div> 49
host = Host,</div><div> 50 port = Port,</div><div> 51 peer_host = PHost,</div><div> 52 peer_port = PPort</div><div> 53 },</div><div> 54 try</div><div> 55 %ok = inet_op(),</div>
<div> 56 inet:setopts(ClientSock, [<font color="#00ff00" size="4">{active, true}</font>]),</div><div> 57 Ret = rcv_loop(State),</div><div> 58 WMsg=lists:flatten(io_lib:<u></u>format("closing connection ~p(~p), "<u></u></div>
<div> 59 "reason: ~p", [Name,self(),Ret])),</div><div> 60 ?DEBUG(WMsg), log:log(warning, ?MODULE, WMsg)</div><div>&nbs
p;61 catch</div><div> 62 E:R -></div><div> 63 EMsg=lists:flatten(io_lib:<u></u>format("closing connection ~p(~p), "<u></u></div><div> 64 "reason: ~p:~p", [Name, self(), E, R])),</div>
<div> 65 ?DEBUG(EMsg), log:log(error, ?MODULE, EMsg)</div><div> 66 after</div><div><div> 66 after</div><div> 67 ?NET:fast_close(ClientSock),</div><div> 68 Msg2=lists:flatten(io_lib:<u></u>format("connection ~p(~p) closed",<u></u></div>
<div> 69 [Name, self()])),</div><div> 70 ?DEBUG(Msg2), log:log(notice, ?MODULE, Msg2)</div><div> 71 end,</div><div> 72 normal.</div><div> 73 </div><div> 74 rcv_loop(#state{sock=Sock}=<u></u>Sta
te) -><u></u></div><div> 75 receive</div><div> 76 {tcp, Sock, Binary} -></div><div> 77 NState = report_run(State, Binary),% calls port_command to send ack pkg</div><div> 78 %inet:setopts(Sock, [{active, once}]),</div>
<div> 79 rcv_loop(NState);</div><div> 80 {tcp_closed, Sock} -> 'peer closed';</div><div> 81 _Other -> rcv_loop(State)</div><div> 82 after ?RCV_TIMEOUT -> 'rcv timeout'</div>
<div> 83 end.</div></div><div><br></div></div><div><br></div><div><br></div><div>Client</div><div><div> 10 -define(TCP_OPTIONS, <font color="#00ff00">[binary, {packet,0}, {active, false},</font></div><div><font color="#00ff00"> 11 &nb
sp; {exit_on_close,true}, {reuseaddr,true}]</font>).</div></div><div><div>101 setup_short_connection(Host, Port, #state{id=Id}=State) -></div><div>102 case gen_tcp:connect(Host, Port, ?TCP_OPTIONS) of</div><div>
103 {ok, Socket} -></div><div>104 ?DEBUG("client(~p) connected to ~p:~p", [Id,Host,Port]),</div><div>105 inet:setopts(Socket, [<font color="#00ff00">{active, once}</font>]),</div><div>106 send_request_and_wait_for_<u></u>response(State#state{socket=<u></u>Socket});<u></u><u></u></div>
<div>107 {error, Reason} -></div><div>108 EMsg=lists:flatten(io_lib:<u></u>format("client(~p) connect failed,"<u></u></div><div>109 "reason: ~p", [Id, Reason])),</div><div>110 ?DEBUG(EMsg),</div>
<div>111 {error, 'connect
failed'}</div><div>112 end.</div><div><div>118 send_request_and_wait_for_<u></u>response(#state{id=Id,requ_<u></u>cnt=RequCnt}=State) -><u></u><u></u></div><div>119 try</div><div>120 Ref = RequCnt,</div>
<div>121 NState = send_request(State, Ref),</div><div>122 wait_for_response(NState, Ref)</div><div>123 catch</div><div>124 E:R -></div><div>125 EMsg = io:format("client(~p) failed in send_request_and_wait_for_<u></u>response"<u></u></div>
<div>126 ", reason: ~p:~p", [Id, E, R]),</div><div>127 ?DEBUG(EMsg),</div><div>128 {error, 'error during send or wait'}</div><div>129 end.</div><div>130 </div><div>131 send_request(#state{socket=<u></u>Sock,requ_cnt=RequCnt}=State, Ref) -><u></u></div>
<div>132
Data = {{"business", "aos"}, {"ref", Ref}},</div><div>133 Pkg = {{"type", "key"}, {"data", Data}},</div><div>134 JPkg = term_to_binary(Pkg),</div>
<div>135 true = erlang:port_command(Sock, JPkg, [nosuspend]),</div><div>136 State#state{requ_cnt=RequCnt-<u></u>1}.<u></u></div><div>137 </div><div>138 wait_for_response(#state{<u></u>socket=Sock}=State, Ref) -><u></u></div>
<div>139 receive</div><div>140 {tcp, Sock, Binary} -></div><div>141 ok = inet:setopts(Sock, [<font color="#00ff00" size="4">{active,once}</font>]),</div><div>142 case report_run(State, Binary, Ref) of</div>
<div>143 {response, NState} -> send_request_and_wait_for_<u></u>response(NState);<u></u></div><div>144 {other, _} -> wait_for_response(State, Ref)</div><div>145
end;</div><div>146 _Other -> wait_for_response(State, Ref)</div><div>147 after 30000 -> {error, 'rcv response timeout'}</div><div>148 end.</div></div><div><br></div></div><div><br>
</div><div>I'm sorry for my poor English. I will be very grateful if someone help me to solve this problem.</div><div><br></div><div style="text-align:right">yours</div><div style="text-align:right">niean</div></span></div>
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