[Bloat] Phoronix: Linux 5.9 to allow FQ_PIE as default

2020-07-15 Thread Rich Brown
Is there any "there" here?

https://www.phoronix.com/forums/forum/phoronix/latest-phoronix-articles/1193738-linux-5-9-to-allow-defaulting-to-fq-pie-queuing-discipline-for-fighting-bufferbloat

Thanks.
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Re: [Bloat] Phoronix: Linux 5.9 to allow FQ_PIE as default

2020-07-15 Thread Toke Høiland-Jørgensen via Bloat
Rich Brown  writes:

> Is there any "there" here?

I'm sorry, what? :)

> https://www.phoronix.com/forums/forum/phoronix/latest-phoronix-articles/1193738-linux-5-9-to-allow-defaulting-to-fq-pie-queuing-discipline-for-fighting-bufferbloat

As far as the patch, allowing fq_pie as default makes sense in that it
is a "works with defaults" type of qdisc. Which as also the reason used
in the patch IIRC.

Not sure why anyone would *want* to run it as default over fq_codel; but
TBH I have never tried it either, so... *shrugs* :)

-Toke
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Re: [Bloat] Phoronix: Linux 5.9 to allow FQ_PIE as default

2020-07-15 Thread Rich Brown
I was asking whether there was anything "there" (that is, interesting) in that 
Phoronix posting / Linux announcement.

> On Jul 15, 2020, at 9:02 AM, Toke Høiland-Jørgensen  wrote:
> 
>> Is there any "there" here?
> 
> I'm sorry, what? :)

Sorry, this is a reference to Gertrude Stein's quote... See Wiktionary - 
https://en.wiktionary.org/wiki/there_is_no_there_there

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Re: [Bloat] Phoronix: Linux 5.9 to allow FQ_PIE as default

2020-07-15 Thread Michael Yartys via Bloat
Are there any major differences between fq_codel and fq_pie in terms of their 
performance? And how does the improved fq_codel called cobalt, which is used in 
cake, stack up?___
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Re: [Bloat] Phoronix: Linux 5.9 to allow FQ_PIE as default

2020-07-15 Thread Jonathan Morton
> On 16 Jul, 2020, at 12:58 am, Michael Yartys via Bloat 
>  wrote:
> 
> Are there any major differences between fq_codel and fq_pie in terms of their 
> performance?

I think some tests were run some time ago which showed significantly better 
behaviour by fq_codel than fq_pie.  In particular, the latter used only a 
single AQM instead of an independent one for each flow.  I'm not sure whether 
it's been changed since then.

The only advantage I can see for PIE over Codel is, possibly, a reduction of 
system load for use of the AQM.  But fq_codel is already pretty efficient so 
that would be an edge case.

In any case, it is already possible to chose any qdisc you like (with default 
parameters) as the default qdisc.  I'm really not sure what the fuss is about.

> And how does the improved fq_codel called cobalt, which is used in cake, 
> stack up?

COBALT has some modifications to basic Codel which, I think, could profitably 
be backported into fq_codel.  It also has a particular extra mode, based on 
BLUE, for dealing with unresponsive traffic (that continued to build queue even 
after lots of ECN signalling and/or Cdel-scheduled packet drops).  It is the 
latter which inspired the name.

For the other major functional component of fq_codel, Cake also has a 
set-associative hash function for allocating flows into queues, which 
substantially reduces the probability of hash collisions in most cases.

 - Jonathan Morton
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