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SubjectRe: TCP push missing with writev()
On Thu, 30 Nov 2000, Andi Kleen wrote:

> > The problem is that if data happens to be written via method (2), then
> > the PUSH flag is never set on any packets generated. This is a bug,
> > surely?
>
> I just tried it on 2.2.17 and 2.4.0test11 and it sets PUSH for writev()
> for both cases just fine. Maybe you could supply a test program and tcpdump
> logs for what you think is wrong ?

BTW, Nagle turned off for all connections.
I can't supply source, but here are some TCP dumps of whats happening.
They're of HTTP, with a Windows IE refreshing a web page. I'll include
just one of the connections.
electra: win98, artemis: 2.4.0-test10

First of all, using write():

18:41:08.714801 electra.1057 > artemis.www: S 984816:984816(0) win 8192 <mss 1460,nop,nop,sackOK> (DF)
18:41:08.714864 artemis.www > electra.1057: S 319022729:319022729(0) ack 984817 win 5840 <mss 1460,nop,nop,sackOK> (DF)
18:41:08.715228 electra.1057 > artemis.www: . ack 1 win 8760 (DF)
18:41:08.734268 electra.1057 > artemis.www: P 1:288(287) ack 1 win 8760 (DF)
18:41:08.734354 artemis.www > electra.1057: . ack 288 win 6432 (DF)
18:41:08.745542 artemis.www > electra.1057: P 1:85(84) ack 288 win 6432 (DF)
18:41:08.754096 electra.1057 > artemis.www: P 288:568(280) ack 85 win 8676 (DF)
18:41:08.754150 artemis.www > electra.1057: . ack 568 win 7504 (DF)
18:41:08.770517 artemis.www > electra.1057: P 85:169(84) ack 568 win 7504 (DF)
18:41:08.825662 electra.1057 > artemis.www: P 568:798(230) ack 169 win 8592 (DF)
18:41:08.825742 artemis.www > electra.1057: . ack 798 win 8576 (DF)
18:41:08.856386 artemis.www > electra.1057: P 169:1230(1061) ack 798 win 8576 (DF)
18:41:08.885806 electra.1057 > artemis.www: R 985614:985614(0) win 0 (DF)

Now using writev() (all of which use two buffers, the second one empty):

18:40:15.434759 electra.1054 > artemis.www: S 931532:931532(0) win 8192 <mss 1460,nop,nop,sackOK> (DF)
18:40:15.434820 artemis.www > electra.1054: S 272275362:272275362(0) ack 931533 win 5840 <mss 1460,nop,nop,sackOK> (DF)
18:40:15.435149 electra.1054 > artemis.www: . ack 1 win 8760 (DF)
18:40:15.468973 electra.1054 > artemis.www: P 1:288(287) ack 1 win 8760 (DF)
18:40:15.469037 artemis.www > electra.1054: . ack 288 win 6432 (DF)
18:40:15.485787 artemis.www > electra.1054: . 1:85(84) ack 288 win 6432 (DF)
18:40:15.592677 electra.1054 > artemis.www: . ack 85 win 8676 (DF)
18:40:15.897950 electra.1054 > artemis.www: P 288:568(280) ack 85 win 8676 (DF)
18:40:15.897977 artemis.www > electra.1054: . ack 568 win 7504 (DF)
18:40:15.900336 artemis.www > electra.1054: . 85:169(84) ack 568 win 7504 (DF)
18:40:16.092696 electra.1054 > artemis.www: . ack 169 win 8592 (DF)
18:40:16.396061 electra.1054 > artemis.www: P 568:798(230) ack 169 win 8592 (DF)
18:40:16.411279 artemis.www > electra.1054: . ack 798 win 8576 (DF)
18:40:16.428007 artemis.www > electra.1054: . 169:1230(1061) ack 798 win 8576 (DF)
18:40:16.592603 electra.1054 > artemis.www: . ack 1230 win 7531 (DF)
18:40:16.895021 electra.1054 > artemis.www: R 932330:932330(0) win 0 (DF)


Ben

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