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Re: TUX and a Java servlet engine



Michael K. Johnson wrote:

Jakob Hummes writes:

Just one question, though: If I understood correctly events to my Java
apps (or servlets) are handled by the tird mechanism you've mentioned. By pushing the event into the user-space would we have to pay a great
performance penalty?


No.  There isn't even context switch overhead, just a single system
call overhead, because it is handled in the same process context,
just switching from kernel mode to user mode.  It gives you memory
protection without any significant performance penalty.

:-)

I have to say, that's great!


I still must say you haven't answered a question I've tried to ask several times. Let me try again.

How is TUX waiting on a socket?

Your answer in the past was "It doesn't. It sends events". I'm not asking how TUX sends HTTP protocol events to a client. Sending events or messages is a standard way of doing this and I simply assumed TUX was doing that. However, how does the kernel get data to TUX? Even the kernel patches for /dev/poll deal with file descriptors... Since Linux doesn't have /dev/poll yet as standard and your only option is select() or poll() it would seem that TUX has the same scalability limitations of all current solutions when you have >500 simultaneous connections.

I'm not saying this is bad or anything. I just want to understand TUX's limitations.


Thanks.






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