On Tue, Nov 17, 2009 at 3:11 PM, clownix wrote:
> Try the following:
>
> tc qdisc del root dev eth0
> tc qdisc add dev eth0 root handle 1: prio
> tc filter add dev eth0 parent 1:0 protocol all u32 match u32 0x00000000
> 0x00000000 at 0 flowid 1:3
> tc filter add dev eth0 parent 1:0 protocol all u32 match u32 0x00E00000
> 0x00E00000 at 0 flowid 1:1
>
>
> ping -Q 255 192.168.1.1
> tc -s class ls dev eth0
>
Thanks for your response.
I tried this on both sides of the ppp link and I see that the filter
is categorizing the pings differently from the miscellaneous http traffic:
tc -s class ls dev ppp0
class prio 1:1 parent 1:
Sent 5124 bytes 61 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
class prio 1:2 parent 1:
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
class prio 1:3 parent 1:
Sent 1144196 bytes 4119 pkt (dropped 68, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
However, the ping statistics are a lot worse when the http traffic is active:
60 packets transmitted, 60 received, 0% packet loss, time 59057ms
rtt min/avg/max/mdev = 5.828/65.577/404.738/90.916 ms
than when it is inactive:
60 packets transmitted, 60 received, 0% packet loss, time 59117ms
rtt min/avg/max/mdev = 5.931/6.747/7.418/0.356 ms
404 msecs maximum ping time when I had http traffic active
versus 7 msecs when it wasn't active. 400 msec difference
corresponds to about 4600 bytes over the 115200 ppp serial
link. The MTU was set to 500 bytes, so I don't understand
where that time is coming from if the pings are being queued
in preference to the http traffic. I'd expect the maximum ping
time to be about 50 msec, not 400 msec. What am I missing?
Thanks,
David
>
> Le mardi 17 novembre 2009 à 14:14 -0800, David L a écrit :
>> Hi,
>>
>> I need to prioritize data sent on a socket over a ppp link
>> so it is transmitted before some other data sharing that link.
>> I googled around for a few days and I thought I understood
>> how I might go about doing this, but my attempts have
>> failed.
>>
>> I thought the default qdisc (pfifo_fast) would prioritize data
>> flagged as "lowdelay" by putting it in a different band that has
>> preferential queuing priority over data in other bands. I
>> attempted to configure the socket like this:
>>
>> int lowdelay = IPTOS_LOWDELAY;
>> return setsockopt(servFd_, IPPROTO_IP, IP_TOS,
>> (void *)&lowdelay, sizeof(lowdelay));
>>
>>
--
To unsubscribe from this list: send the line "unsubscribe linux-net" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
