linux-kernel - Re: [PATCH] net: sched: make default fifo qdiscs appear in the dump

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Date:   Fri, 21 Oct 2016 04:36:57 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Jiri Kosina <jikos@...nel.org>
Cc:     Jamal Hadi Salim <jhs@...atatu.com>, Phil Sutter <phil@....cc>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S. Miller" <davem@...emloft.net>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] net: sched: make default fifo qdiscs appear in the dump

On Fri, 2016-10-21 at 10:45 +0200, Jiri Kosina wrote:
> The original reason [1] for having hidden qdiscs (potential scalability 
> issues in qdisc_match_from_root() with single linked list in case of large 
> amount of qdiscs) has been invalidated by 59cc1f61f0 ("net: sched: convert 
> qdisc linked list to hashtable").
> 
> This allows us for bringing more clarity and determinism into the dump by 
> making default pfifo qdiscs visible.
> 
> [1] http://lkml.kernel.org/r/1460732328.10638.74.camel@edumazet-glaptop3.roam.corp.google.com
> 
> Signed-off-by: Jiri Kosina <jkosina@...e.cz>
> ---

Some of us are dealing with huge HTB hierarchies, so adding default fifo
in the dump will add more data pumped from the kernel.

BwE [1] for instance dumps qdisc/classes every 5 seconds.

I guess we'll need to not pull this patch in our kernels.

This reminds me of an HTB patch to avoid dumping rate estimates for HTB.

I will send it today.
 
[1]
http://static.googleusercontent.com/media/research.google.com/en//pubs/archive/43838.pdf