Messages in this thread | | | Date | Thu, 18 Jan 2001 14:29:44 +0100 (CET) | From | Ingo Molnar <> | Subject | Re: [Fwd: [Fwd: Is sendfile all that sexy? (fwd)]] |
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On Wed, 17 Jan 2001, Rick Jones wrote:
> certainly, i see by your examples how cork can make life easier on the > developer - they can putc() the reply if they want. for a persistent > http connection, there would be the cork and uncork each time, for a > pipelined connection, it is basically a race - how does the client > present requests to the connection, what are the speeds of that > connection relative to the speed of the server getting replies into > the socket that sort of thing.
such dynamic properties should IMO never become visible to user-space interfaces i believe. TCP_CORK/MSG_MORE (which are both the same thing, in a different interface) are a way to specify logical neighborhood of app-side SENDs. I believe the most sensible and generic thing to do is to require MSG_MORE information from the application: 'is it likely that the application is going to SEND something soon, or not?'.
Submitting an exact timetable of planned future SENDs (with a fully specified probability distribution of every expected future SEND event) would be the most informative thing to do, but this is not very practical.
Basically MSG_MORE is a simplified probability distribution of the next SEND, and it already covers all the other (iovec, nagle, TCP_CORK) mechanizm available, in a surprisingly easy way IMO. I believe MSG_MORE is very robust from a theoreticaly point of view.
To use this information to judge saturation situations properly is completely up to the stack.
Ingo
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