Re: [Fwd: [Fwd: Is sendfile all that sexy? (fwd)]]

[Rick Jones]

Ingo Molnar wrote:
> 
> On Wed, 17 Jan 2001, Rick Jones wrote:
> 
> > i'd heard interesting generalities but no specifics. for instance,
> > when the send is small, does TCP wait exclusively for the app to
> > flush, or is there an "if all else fails" sort of timer running?
> 
> yes there is a per-socket timer for this. According to RFC 1122 a TCP
> stack 'MUST NOT' buffer app-sent TCP data indefinitely if the PSH bit
> cannot be explicitly set by a SEND operation. Was this a trick question?
> :-)

Nope, not a trick question. The nagle heuristic means that small sends
will not wait indefinitely since sending the first small bit of data
starts the retransmission timer as a course of normal processing. So, I
am not in the habit of thinking about a "clear the buffer" timer being
set when a small send takes place but no transmit happens.

rick jones

btw, as I'm currently on linux-kernel, no need to cc me :)
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