netdev - Re: [PATCH net-next v3 0/7] net: sched: pie: align PIE implementation with RFC 8033

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Date:   Mon, 25 Feb 2019 16:38:11 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Leslie Monis <lesliemonis@...il.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        "Mohit P . Tahiliani" <tahiliani@...k.edu.in>,
        Dave Taht <dave.taht@...il.com>,
        Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: [PATCH net-next v3 0/7] net: sched: pie: align PIE
 implementation with RFC 8033

On Tue, 26 Feb 2019 00:39:54 +0530
Leslie Monis <lesliemonis@...il.com> wrote:

> The current implementation of the PIE queuing discipline is according to the
> IETF draft [http://tools.ietf.org/html/draft-pan-aqm-pie-00] and the paper
> [PIE: A Lightweight Control Scheme to Address the Bufferbloat Problem].
> However, a lot of necessary modifications and enhancements have been proposed
> in RFC 8033, which have not yet been incorporated in the source code of Linux.
> This patch series helps in achieving the same.
> 
> Performance tests carried out using Flent [https://flent.org/]
> 
> Changes from v2 to v3:
>   - Used div_u64() instead of direct division after explicit type casting as
>     recommended by David
> 
> Changes from v1 to v2:
>   - Excluded the patch setting PIE dynamically active/inactive as the test
>     results were unsatisfactory
>   - Fixed a scaling issue when adding more auto-tuning cases which caused
>     local variables to underflow
>   - Changed the long if/else chain to a loop as suggested by Stephen
>   - Changed the position of the accu_prob variable in the pie_vars
>     structure as recommended by Stephen
> 
> Mohit P. Tahiliani (7):
>   net: sched: pie: change value of QUEUE_THRESHOLD
>   net: sched: pie: change default value of pie_params->target
>   net: sched: pie: change default value of pie_params->tupdate
>   net: sched: pie: change initial value of pie_vars->burst_time
>   net: sched: pie: add more cases to auto-tune alpha and beta
>   net: sched: pie: add derandomization mechanism
>   net: sched: pie: update references
> 
>  include/uapi/linux/pkt_sched.h |   2 +-
>  net/sched/sch_pie.c            | 107 ++++++++++++++++++++-------------
>  2 files changed, 66 insertions(+), 43 deletions(-)

Are you concerned at all that changes to default values might change
expected behavior of existing users?