Quoting Burak Gorkemli:
| Arnaldo,
|
| Setting tx_qlen=0 did not help, the receiver receives only 1 packet, despite of sender's sending 10 packets. Attached are the dmesg output of sender & receiver. I modified the DCCP code on the sender side to print some debug messages (input/output to/from functions, etc.).
|
| BTW, I am using CCID3.
|
Thank you very much for this input. I have been running the same tests and I think I have found one solution
to this problem already. The nofeedback timer is set according to the book, i.e. max(4*R, 2*s/X). On LANS,
RTTs are small and hence the nofeedback timer expires horribly often (every two jiffies). This further halves
the sending rate each time. And since we don't have the integer sending rate computation fixed, the sending
rate therefore very quickly converges towards zero.
I can see that in your client log the feedback timer is also triggered very often, but I don't see the
messages when they are triggered (is CONFIG_IP_DCCP_CCID3_DEBUG enabled)?
This has been a recent patch; I am working on a configuration option to use a higher RTO value (the 1 second
that TCP uses), which will
a) restore the previous state
b) make it possible to experiment with different RTO values
I hope to send the patch within the next hour or so, subject to some testing.
Many thanks
Gerrit
|
| ----- Original Message ----
| From: Arnaldo Carvalho de Melo <arnaldo.melo@xxxxxxxxx>
| To: Ian McDonald <ian.mcdonald@xxxxxxxxxxx>
| Cc: Leandro Melo de Sales <leandroal@xxxxxxxxx>; burak gorkemli <burakgorkemli@xxxxxxxxx>; DCCP Mailing List <dccp@xxxxxxxxxxxxxxx>
| Sent: Thursday, November 30, 2006 12:51:11 PM
| Subject: Re:
|
| On 11/29/06, Ian McDonald <ian.mcdonald@xxxxxxxxxxx> wrote:
| > Folks,
| >
| > Another thing to note is that with a limit on tx queue sizes now you
| > will get EAGAIN if the queue is full...
|
| Yes, 4, 5 packets should be, in dccp_sendmsg:
|
| if (sysctl_dccp_tx_qlen &&
| (sk->sk_write_queue.qlen >= sysctl_dccp_tx_qlen)) {
| rc = -EAGAIN;
| goto out_release;
| }
|
| Leandro and Burak: could you please try setting sysctl_dccp_tx_qlen to
| zero? doing this:
|
| [root@qemu ~]# cat /proc/sys/net/dccp/default/tx_qlen
| 5
| [root@qemu ~]# echo 0 > /proc/sys/net/dccp/default/tx_qlen
| [root@qemu ~]# cat /proc/sys/net/dccp/default/tx_qlen
| 0
| [root@qemu ~]#
|
| And report the results?
|
| - Arnaldo
| -
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|
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