Asio does add-and-remove on every operation which is a bit of a problem here. Doing reads util the data is exhausted won't help. I think that it can even hurt because blocking system call will put thread to sleep if there is no data and also block other consumers running of the same "io_service" (run () is called by a single thread). In case of multicast, I always get complete packet (or nothing). The background is that I have a client application for server(s) pushing tremendous amount of data over multicast. Latency is a huge concern (we are talking sub*micro*seconds). So locking on epoll to add/remove events (or doing blocking calls) hurts. Basically, I optimized everything - from not calling "bind" every time, not copying function internals, and re-using the same pre-allocated memory to store state associated with read. Re-registering event in epoll is the last thing. I hope to find a way to stick this feature into Asio or somehow get epoll internals and work with this socket myself. Thanks, Vlad On Wed, Mar 23, 2011 at 4:58 PM, Gruenke, Matt <mgruenke@tycoint.com> wrote:
Can't you simply put the descriptor in non-blocking mode and, in your async_read handler, perform further non-async reads until the waiting data is exhausted? I don't know how ASIO uses epoll, but if it's doing an add-and-remove for every async operation, you'd at least get rid of the overhead of extra adds & removes while data is still wating.
Matt
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From: boost-bounces@lists.boost.org on behalf of Vlad Lazarenko Sent: Wed 3/23/2011 4:27 PM To: boost@lists.boost.org Subject: [boost] Asio - is it possible not to remove descriptor from epoll?
Guys,
Is it possible to make ASIO keep descriptor in epoll and not remove it automatically after event is fired (and implement or emulate the same behavior for other mechanisms like select, kqueue etc)? My use case is very simple - I am reading data from multicast socket. One read at a time, always reusing the same buffer. The performance is very critical. Another use case is to give ASIO a null buffer and perform sync read yourself when data is available, in that case you can read from tcp/ip sockets as well. I know that libevent supports this but was not able to find out how to do it with Asio. If it is not available, would someone be able to assist in adding this feature?
Thank you, Vlad
-- *Vlad Lazarenko* *Lazarenko.me <http://lazarenko.me>* vlad@lazarenko.com <vlad@lazarenko.me> _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
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