[ENet-discuss] CPU Usage

[Nicholas J Ingrassellino]

I am running a little experiment in C++ using ENet v1.3.0 with MSVC 2k8. 
What I am attempting to create is a pure dumb terminal-style application 
where all video is done on a remote server and sent to the client while 
the client only sends over key presses. Yes, yes, I know; I am 
reinventing the wheel and half the people reading this do not approve. 
It is just an experiment I am doing for kicks.

My issue lies in ENet's CPU usage. I had noticed that during the 
receiving/drawing step my client CPU usage went to 100% and was reacting 
way too slow to do what I want to do. After a while I have narrowed the 
problem down to ENet. I even went as far as taking ENet out of the 
picture to be sure it was not something else using simulated data as if 
it were received from the server (IE virtually not changing my client 
main loop). Just so I have gone on the record as saying it the client, 
once ENet is removed from the picture, can draw an image, pixel by 
pixel, 60 times a second without breaking a sweat.

My server is sending 7 bytes (payload, of course) for each pixel. At 
800x600x24 I am aware this is a hell of a lot of data but it is still 
eating a lot more CPU than I figured it would on the client. The server 
gets all the data off in a timely fashion but the receiving side can not 
get it nearly as fast as it was sent so it ends up backing up really 
quickly. The client code looks like this:

    while ( !main_loop_exit ) {
         acquire_screen();
         blit(buffer, screen, 0, 0, 0, 0, buffer->w, buffer->h);
         release_screen();

         if ( keypressed() ) {
             unsigned char key_next = readkey() & 0xff;
             ENetPacket *packet = enet_packet_create(&key_next,
    sizeof(unsigned char), ENET_PACKET_FLAG_RELIABLE);
             enet_peer_send(peer, 0, packet);
         }

         if ( enet_host_service(client, &event, 0) > 0 ) {
             if ( event.type == ENET_EVENT_TYPE_RECEIVE ) {
                 _putpixel24(buffer, ((PACKET_PAYLOAD
    *)event.packet->data)->x, ((PACKET_PAYLOAD *)event.packet->data)->y,
    makecol(((PACKET_PAYLOAD *)event.packet->data)->r, ((PACKET_PAYLOAD
    *)event.packet->data)->g, ((PACKET_PAYLOAD *)event.packet->data)->b));
                 enet_packet_destroy(event.packet);
             }
             else if ( event.type == ENET_EVENT_TYPE_DISCONNECT )
                 main_loop_exit = true;
         }
         else
             rest(1);
    }


Any input on how I can speed up ENet's processing of packets would be 
greatly appreciated. I think ENet is a perfect fit for this project on 
paper if I can just figure out how to make it sing.

------------------------------------------------------------------------

Nicholas J Ingrassellino
LifebloodNetworks.com <http://www.lifebloodnetworks.com/> || 
nick at lifebloodnetworks.com <mailto:nick at lifebloodnetworks.com>

"The idea that I can be presented with a problem, set out to logically 
solve it with the tools at hand, and wind up with a program that could 
not be legally used because someone else followed the same logical steps 
some years ago and filed for a patent on it is horrifying."
- John Carmack on software patents

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.cubik.org/pipermail/enet-discuss/attachments/20100926/263b82cd/attachment.html>