[LARTC] When the inside functions of a sfq are called ?

[LARTC] When the inside functions of a sfq are called ?

[Adrian Saileanu]

  I read the sched/qdiscs code from kernel source ... and I have some
questions :

  When the .enqueue, .dequeue, .drop, .requeue functions are called ? What
is the event that triggers them and how often this event apears ( per
second ? ) ? When a qdisc is dequeued ( when it's limit is reached ) ?

  Thanks





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Re: [LARTC] When the inside functions of a sfq are called ?

[Roy]

Logicaly it would be so:
enqueue caled by last(leaf) filter
dequeue called by htb
drop should not be used in normal operation, probably called on "tc dev eth0
del root"

(this is what I think it should be not nessecary t is so)

----- Original Message ----- 
From: "Adrian Saileanu" <adrian@smartcall.ro>
To: <lartc@mailman.ds9a.nl>
Sent: Thursday, April 15, 2004 8:10 PM
Subject: [LARTC] When the inside functions of a sfq are called ?


>
>   I read the sched/qdiscs code from kernel source ... and I have some
> questions :
>
>   When the .enqueue, .dequeue, .drop, .requeue functions are called ? What
> is the event that triggers them and how often this event apears ( per
> second ? ) ? When a qdisc is dequeued ( when it's limit is reached ) ?
>
>   Thanks
>
>
>
>
>
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
>

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Re: [LARTC] When the inside functions of a sfq are called ?

[Adrian Saileanu]

> Logicaly it would be so:
> enqueue caled by last(leaf) filter
> dequeue called by htb
> drop should not be used in normal operation, probably called on "tc dev
eth0 del root"

  I think .drop is not being called when the qdisc gets deleted ...
Haven't you ever seen droped pachets when looking at the statistics by a
qdisc ? I suspect that htb is also calling this function whenever the
bandwith requested by the qdisk is not big enough !

>
> (this is what I think it should be not nessecary t is so)
>
> ----- Original Message -----
> From: "Adrian Saileanu" <adrian@smartcall.ro>
> To: <lartc@mailman.ds9a.nl>
> Sent: Thursday, April 15, 2004 8:10 PM
> Subject: [LARTC] When the inside functions of a sfq are called ?
>
>
>>
>>   I read the sched/qdiscs code from kernel source ... and I have some
>> questions :
>>
>>   When the .enqueue, .dequeue, .drop, .requeue functions are called ?
>> What
>> is the event that triggers them and how often this event apears ( per
>> second ? ) ? When a qdisc is dequeued ( when it's limit is reached ) ?
>>
>>   Thanks
>>
>>
>>
>>
>>
>> _______________________________________________
>> LARTC mailing list / LARTC@mailman.ds9a.nl
>> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
>>
>
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
>


Adrian Saileanu
Netmaster Communications Srl

address: Str. Ion Brezoianu Nr. 20
Sector 1, Bucuresti, Romania

office: +40 21 315 92 00
mobile: +40 723 979 586
email:   adrian@smartcall.ro





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Re: [LARTC] When the inside functions of a sfq are called ?

[Roy]

----- Original Message ----- 
From: "Adrian Saileanu" <adrian@smartcall.ro>
To: "Roy" <roy@xxx.lt>
Cc: <lartc@mailman.ds9a.nl>
Sent: Friday, April 16, 2004 3:24 PM
Subject: Re: [LARTC] When the inside functions of a sfq are called ?


>
> > Logicaly it would be so:
> > enqueue caled by last(leaf) filter
> > dequeue called by htb
> > drop should not be used in normal operation, probably called on
> '"'tc dev
> eth0 del root'"'
>
>   I think .drop is not being called when the qdisc gets deleted ...
> Haven't you ever seen droped pachets when looking at the statistics by a
> qdisc ? I suspect that htb is also calling this function whenever the
> bandwith requested by the qdisk is not big enough !

No, that is incorrect, when qdisc gets deleted its statistic also gets
deleted,
and if you are downloading at that time you may notice that downloads stops
for short time
so pakets are deleted, or else who will dequeue them if you deleted htb?



> >
> > (this is what I think it should be not nessecary t is
> so)
> >
> > ----- Original Message -----
> > From: '"'Adrian Saileanu'"'
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
> >>
> >
> > _______________________________________________
> > LARTC mailing list / LARTC@mailman.ds9a.nl
> > http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
> >
>
>
> Adrian Saileanu
> Netmaster Communications Srl
>
> address: Str. Ion Brezoianu Nr. 20
> Sector 1, Bucuresti, Romania
>
> office: +40 21 315 92 00
> mobile: +40 723 979 586
> email:   adrian@smartcall.ro
>
>
>
>
>
>

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Re: [LARTC] When the inside functions of a sfq are called ?

[Andy Furniss]

Adrian Saileanu wrote:
>   I read the sched/qdiscs code from kernel source ... and I have some
> questions :
> 
>   When the .enqueue, .dequeue, .drop, .requeue functions are called ?

Do you mean in sfq.c - ie sfq_enqueue etc. Maybe you mean something else.

  What
> is the event that triggers them and how often this event apears ( per
> second ? ) ?

I don't know as such, but always assumed that when attached to HTB  - a 
packet gets enqueued if there aren't enough (c)tokens to send it and 
dequeued when there are. As for timing I don't think sfq uses any - it's 
up to whatever it is attached to.

sfq_drop is called from sfq_enqueue when the queue is full. It drops 
from the longest slot.

requeue - don't know.

Andy.

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Re: [LARTC] When the inside functions of a sfq are called ?

[Adrian Saileanu]

> Adrian Saileanu wrote:
>>   I read the sched/qdiscs code from kernel source ... and I have some
>> questions :
>>
>>   When the .enqueue, .dequeue, .drop, .requeue functions are called ?
>
> Do you mean in sfq.c - ie sfq_enqueue etc. Maybe you mean something else.

Yes, I ment the functions in the Qdisc_ops struct :

+static struct Qdisc_ops dup_qdisc_ops = {
+        .next                = NULL,
+        .cl_ops                = NULL,
+        .id                = "sfq",
+        .priv_size        = sizeof(struct sfq_sched_data),
+        .enqueue        = sfq_enqueue,
+        .dequeue        = sfq_dequeue,
+        .requeue        = sfq_requeue,
+        .drop                = sfq_drop,
+        .init                = sfq_init,
+        .reset                = sfq_reset,
+        .destroy        = NULL,
+        .change                = sfq_init,
+        .dump                = sfq_dump,
+        .owner                = THIS_MODULE,
+};


>   What
>> is the event that triggers them and how often this event apears ( per
>> second ? ) ?
>
> I don't know as such, but always assumed that when attached to HTB  - a
> packet gets enqueued if there aren't enough (c)tokens to send it and
> dequeued when there are. As for timing I don't think sfq uses any - it's
> up to whatever it is attached to.
>

  Ok, the packet gets enqueued ... and the queue gets full. Then if a new
packet arrives and the queue is still full (  it has not been dequeued )
then this packet is dropped. My question is ... is the queue dequeued
when it is full ? Or t can be dequeued even when the maximum has not
been reatched ? When this .dequeue function is called ?

> sfq_drop is called from sfq_enqueue when the queue is full. It drops
> from the longest slot.
>
  I know this ...

> requeue - don't know.
>
> Andy.
>
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
>


Adrian Saileanu
Netmaster Communications Srl

address: Str. Ion Brezoianu Nr. 20
Sector 1, Bucuresti, Romania

office: +40 21 315 92 00
mobile: +40 723 979 586
email:   adrian@smartcall.ro





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Re: [LARTC] When the inside functions of a sfq are called ?

[Andy Furniss]

Adrian Saileanu wrote:
>>Adrian Saileanu wrote:
>>
>>>  I read the sched/qdiscs code from kernel source ... and I have some
>>>questions :
>>>
>>>  When the .enqueue, .dequeue, .drop, .requeue functions are called ?
>>
>>Do you mean in sfq.c - ie sfq_enqueue etc. Maybe you mean something else.
> 
> 
> Yes, I ment the functions in the Qdisc_ops struct :
> 
> +static struct Qdisc_ops dup_qdisc_ops = {
> +        .next                = NULL,
> +        .cl_ops                = NULL,
> +        .id                = "sfq",
> +        .priv_size        = sizeof(struct sfq_sched_data),
> +        .enqueue        = sfq_enqueue,
> +        .dequeue        = sfq_dequeue,
> +        .requeue        = sfq_requeue,
> +        .drop                = sfq_drop,
> +        .init                = sfq_init,
> +        .reset                = sfq_reset,
> +        .destroy        = NULL,
> +        .change                = sfq_init,
> +        .dump                = sfq_dump,
> +        .owner                = THIS_MODULE,
> +};
> 
> 
> 
>>  What
>>
>>>is the event that triggers them and how often this event apears ( per
>>>second ? ) ?
>>
>>I don't know as such, but always assumed that when attached to HTB  - a
>>packet gets enqueued if there aren't enough (c)tokens to send it and
>>dequeued when there are. As for timing I don't think sfq uses any - it's
>>up to whatever it is attached to.
>>
> 
> 
>   Ok, the packet gets enqueued ... and the queue gets full. Then if a new
> packet arrives and the queue is still full (  it has not been dequeued )
> then this packet is dropped. 

I think a packet gets enqueued - then the queue length is checked and if 
it's full sfq_drop is called. sfq_drop drops a packet from the longest 
slot - hence the packet that filled the queue may or may not be the one 
that is dropped depending on which slot it got hashed to.

> My question is ... is the queue dequeued
> when it is full ? Or t can be dequeued even when the maximum has not
> been reatched ? When this .dequeue function is called ?

It is normal for dequeue to be called before the queue is full - exactly 
when it gets called is the job of whatever the sfq got attached to.

Andy.

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