[LARTC] hfsc and dropped packets

[LARTC] hfsc and dropped packets

[James Nelson]

Hi,
 
I'm trying to get a handle on hfsc.  Here is my configuration:

root@jmnrouter:/jmn# tc  class show dev vlan1
class hfsc 1: root
class hfsc 1:1 parent 1: ls m1 0bit d 0us m2 225000bit ul m1 0bit d 0us m2
225000bit
class hfsc 1:10 parent 1:1 rt m1 191000bit d 25.0ms m2 135000bit ls m1 0bit
d 0us m2 135000bit ul m1 0bit d 0us m2 225000bit
class hfsc 1:20 parent 1:1 rt m1 22008bit d 25.0ms m2 56008bit ls m1 0bit d
0us m2 56008bit ul m1 0bit d 0us m2 225000bit
class hfsc 1:30 parent 1:1 rt m1 11008bit d 25.0ms m2 22008bit ls m1 0bit d
0us m2 22008bit ul m1 0bit d 0us m2 225000bit
class hfsc 1:40 parent 1:1 rt m1 0bit d 25.0ms m2 11008bit ls m1 0bit d 0us
m2 11008bit ul m1 0bit d 0us m2 225000bit

And here is the stats right after I run the qos script with no load on the
link(adsl):
root@jmnrouter:/jmn# tc -s class show dev vlan1
class hfsc 1: root
 Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
 period 0 level 2

class hfsc 1:1 parent 1: ls m1 0bit d 0us m2 225000bit ul m1 0bit d 0us m2
225000bit
 Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
 period 349 work 42417 bytes level 1

class hfsc 1:10 parent 1:1 rt m1 191000bit d 25.0ms m2 135000bit ls m1 0bit
d 0us m2 135000bit ul m1 0bit d 0us m2 225000bit
 Sent 31297 bytes 304 pkts (dropped 18, overlimits 0)
 period 304 work 31297 bytes rtwork 30991 bytes level 0

class hfsc 1:20 parent 1:1 rt m1 22008bit d 25.0ms m2 56008bit ls m1 0bit d
0us m2 56008bit ul m1 0bit d 0us m2 225000bit
 Sent 7302 bytes 17 pkts (dropped 2, overlimits 0)
 period 17 work 7302 bytes rtwork 7010 bytes level 0

class hfsc 1:30 parent 1:1 rt m1 11008bit d 25.0ms m2 22008bit ls m1 0bit d
0us m2 22008bit ul m1 0bit d 0us m2 225000bit
 Sent 3818 bytes 28 pkts (dropped 0, overlimits 0)
 period 28 work 3818 bytes rtwork 3818 bytes level 0

class hfsc 1:40 parent 1:1 rt m1 0bit d 25.0ms m2 11008bit ls m1 0bit d 0us
m2 11008bit ul m1 0bit d 0us m2 225000bit
 Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
 period 0 level 0


Why is there dropped packets but nothing overlimits??

Thanks.


FYI Here is the relevant scipt commands I have dsl 1.5down and 256up.
+ tc qdisc del dev vlan1 root
+ tc qdisc add dev vlan1 root handle 1: hfsc default 30
+ tc class add dev vlan1 parent 1: classid 1:1 hfsc ls rate 225kbit ul rate
225kbit
+ tc class add dev vlan1 parent 1:1 classid 1:10 hfsc rt m1 191kbit d 25ms
m2 135kbit ls rate 135kbit ul rate 225kbit
+ tc class add dev vlan1 parent 1:1 classid 1:20 hfsc rt m1 22kbit d 25ms m2
56kbit ls rate 56kbit ul rate 225kbit
+ tc class add dev vlan1 parent 1:1 classid 1:30 hfsc rt m1 11kbit d 25ms m2
22kbit ls rate 22kbit ul rate 225kbit
+ tc class add dev vlan1 parent 1:1 classid 1:40 hfsc rt m1 0kbit d 25ms m2
11kbit ls rate 11kbit ul rate 225kbit
+ tc filter add dev vlan1 parent 1: prio 1 protocol ip handle 1 fw flowid
1:10
+ tc filter add dev vlan1 parent 1: prio 2 protocol ip handle 2 fw flowid
1:20
+ tc filter add dev vlan1 parent 1: prio 3 protocol ip handle 3 fw flowid
1:30
+ tc filter add dev vlan1 parent 1: prio 4 protocol ip handle 4 fw flowid
1:40

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Re: [LARTC] hfsc and dropped packets

[Patrick McHardy]

James Nelson wrote:
> Hi,
>  
> I'm trying to get a handle on hfsc.  Here is my configuration:
> 
> root@jmnrouter:/jmn# tc  class show dev vlan1
> class hfsc 1: root
> class hfsc 1:1 parent 1: ls m1 0bit d 0us m2 225000bit ul m1 0bit d 0us m2
> 225000bit
> class hfsc 1:10 parent 1:1 rt m1 191000bit d 25.0ms m2 135000bit ls m1 0bit
> d 0us m2 135000bit ul m1 0bit d 0us m2 225000bit
> class hfsc 1:20 parent 1:1 rt m1 22008bit d 25.0ms m2 56008bit ls m1 0bit d
> 0us m2 56008bit ul m1 0bit d 0us m2 225000bit
> class hfsc 1:30 parent 1:1 rt m1 11008bit d 25.0ms m2 22008bit ls m1 0bit d
> 0us m2 22008bit ul m1 0bit d 0us m2 225000bit
> class hfsc 1:40 parent 1:1 rt m1 0bit d 25.0ms m2 11008bit ls m1 0bit d 0us
> m2 11008bit ul m1 0bit d 0us m2 225000bit
> 
> And here is the stats right after I run the qos script with no load on the
> link(adsl):
> root@jmnrouter:/jmn# tc -s class show dev vlan1
> class hfsc 1: root
>  Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
>  period 0 level 2
> 
> class hfsc 1:1 parent 1: ls m1 0bit d 0us m2 225000bit ul m1 0bit d 0us m2
> 225000bit
>  Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
>  period 349 work 42417 bytes level 1
> 
> class hfsc 1:10 parent 1:1 rt m1 191000bit d 25.0ms m2 135000bit ls m1 0bit
> d 0us m2 135000bit ul m1 0bit d 0us m2 225000bit
>  Sent 31297 bytes 304 pkts (dropped 18, overlimits 0)
>  period 304 work 31297 bytes rtwork 30991 bytes level 0
> 
> class hfsc 1:20 parent 1:1 rt m1 22008bit d 25.0ms m2 56008bit ls m1 0bit d
> 0us m2 56008bit ul m1 0bit d 0us m2 225000bit
>  Sent 7302 bytes 17 pkts (dropped 2, overlimits 0)
>  period 17 work 7302 bytes rtwork 7010 bytes level 0
> 
> class hfsc 1:30 parent 1:1 rt m1 11008bit d 25.0ms m2 22008bit ls m1 0bit d
> 0us m2 22008bit ul m1 0bit d 0us m2 225000bit
>  Sent 3818 bytes 28 pkts (dropped 0, overlimits 0)
>  period 28 work 3818 bytes rtwork 3818 bytes level 0
> 
> class hfsc 1:40 parent 1:1 rt m1 0bit d 25.0ms m2 11008bit ls m1 0bit d 0us
> m2 11008bit ul m1 0bit d 0us m2 225000bit
>  Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
>  period 0 level 0
> 
> 
> Why is there dropped packets but nothing overlimits??

Overlimits counts dequeue-attempts that were unsuccessful because of
qdisc limits. Drops usually occur when the inner qdisc is full during
enqueue, so they have quite opposite meanings.
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Re: [LARTC] hfsc and dropped packets

[Patrick McHardy]

Patrick McHardy wrote:
> James Nelson wrote:
> 
>>root@jmnrouter:/jmn# tc  class show dev vlan1
>> [...]
>>
>>Why is there dropped packets but nothing overlimits??
> 
> 
> Overlimits counts dequeue-attempts that were unsuccessful because of
> qdisc limits. Drops usually occur when the inner qdisc is full during
> enqueue, so they have quite opposite meanings.

BTW, in your case the drops most likely occur because HFSC's default
pfifo child qdiscs use the tx_queue_len of the device as their limit,
which in case of vlan devices is zero (in that case 1 is used).

So you can either increase the tx_queue_len of the vlan device
or manually add child qdiscs with bigger limits.
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RE: [LARTC] hfsc and dropped packets

[James Nelson]

Thanks for the reply!  Setting the tx_queue_len fixed the drops which got
rid of the studder in voip! Thanks. 

-----Original Message-----
From: Patrick McHardy [mailto:kaber@trash.net] 
Sent: Monday, March 13, 2006 6:03 PM
To: James Nelson
Cc: lartc@mailman.ds9a.nl
Subject: Re: [LARTC] hfsc and dropped packets

Patrick McHardy wrote:
> James Nelson wrote:
> 
>>root@jmnrouter:/jmn# tc  class show dev vlan1  [...]
>>
>>Why is there dropped packets but nothing overlimits??
> 
> 
> Overlimits counts dequeue-attempts that were unsuccessful because of 
> qdisc limits. Drops usually occur when the inner qdisc is full during 
> enqueue, so they have quite opposite meanings.

BTW, in your case the drops most likely occur because HFSC's default pfifo
child qdiscs use the tx_queue_len of the device as their limit, which in
case of vlan devices is zero (in that case 1 is used).

So you can either increase the tx_queue_len of the vlan device or manually
add child qdiscs with bigger limits.

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