netdev - Re: [PATCH net-next 4/4] net_sched: sch_fq: add TCA_FQ

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Message-ID: <87bkdhgsa4.fsf@toke.dk>
Date: Mon, 02 Oct 2023 13:47:31 +0200
From: Toke Høiland-Jørgensen <toke@...hat.com>
To: Eric Dumazet <edumazet@...gle.com>, "David S . Miller"
 <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
 <pabeni@...hat.com>
Cc: Willem de Bruijn <willemb@...gle.com>, Soheil Hassas Yeganeh
 <soheil@...gle.com>, Neal Cardwell <ncardwell@...gle.com>, Jamal Hadi
 Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko
 <jiri@...nulli.us>, netdev@...r.kernel.org, eric.dumazet@...il.com, Eric
 Dumazet <edumazet@...gle.com>
Subject: Re: [PATCH net-next 4/4] net_sched: sch_fq: add TCA_FQ_WEIGHTS
 attribute

Eric Dumazet <edumazet@...gle.com> writes:

> This attribute can be used to tune the per band weight
> and report them in "tc qdisc show" output:
>
> qdisc fq 802f: parent 1:9 limit 100000p flow_limit 500p buckets 1024 orphan_mask 1023
>  quantum 8364b initial_quantum 41820b low_rate_threshold 550Kbit
>  refill_delay 40ms timer_slack 10us horizon 10s horizon_drop
>  bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1 weights 589824 196608 65536
>  Sent 236460814 bytes 792991 pkt (dropped 0, overlimits 0 requeues 0)
>  rate 25816bit 10pps backlog 0b 0p requeues 0
>   flows 4 (inactive 4 throttled 0)
>   gc 0 throttled 19 latency 17.6us fastpath 773882
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> ---
>  include/uapi/linux/pkt_sched.h |  3 +++
>  net/sched/sch_fq.c             | 32 ++++++++++++++++++++++++++++++++
>  2 files changed, 35 insertions(+)
>
> diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h
> index ec5ab44d41a2493130670870dc9e68c71187740f..f762a10bfb78ed896d8a5b936045a956d97b3831 100644
> --- a/include/uapi/linux/pkt_sched.h
> +++ b/include/uapi/linux/pkt_sched.h
> @@ -943,12 +943,15 @@ enum {
>  
>  	TCA_FQ_PRIOMAP,		/* prio2band */
>  
> +	TCA_FQ_WEIGHTS,		/* Weights for each band */
> +
>  	__TCA_FQ_MAX
>  };
>  
>  #define TCA_FQ_MAX	(__TCA_FQ_MAX - 1)
>  
>  #define FQ_BANDS 3
> +#define FQ_MIN_WEIGHT 16384
>  
>  struct tc_fq_qd_stats {
>  	__u64	gc_flows;
> diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
> index 1bae145750a66f769bd30f1db09203f725801249..1a411fe36c79a86635f319c230a045d653571700 100644
> --- a/net/sched/sch_fq.c
> +++ b/net/sched/sch_fq.c
> @@ -919,6 +919,10 @@ static const struct nla_policy fq_policy[TCA_FQ_MAX + 1] = {
>  			.type = NLA_BINARY,
>  			.len = sizeof(struct tc_prio_qopt),
>  		},
> +	[TCA_FQ_WEIGHTS]		= {
> +			.type = NLA_BINARY,
> +			.len = FQ_BANDS * sizeof(s32),
> +		},
>  };
>  
>  /* compress a u8 array with all elems <= 3 to an array of 2-bit fields */
> @@ -941,6 +945,24 @@ static void fq_prio2band_decompress_crumb(const u8 *in, u8 *out)
>  		out[i] = fq_prio2band(in, i);
>  }
>  
> +static int fq_load_weights(struct fq_sched_data *q,
> +			   const struct nlattr *attr,
> +			   struct netlink_ext_ack *extack)
> +{
> +	s32 *weights = nla_data(attr);
> +	int i;
> +
> +	for (i = 0; i < FQ_BANDS; i++) {
> +		if (weights[i] < FQ_MIN_WEIGHT) {
> +			NL_SET_ERR_MSG_MOD(extack, "Incorrect weight");

As in the previous patch, can we be a bit more specific here? "Weight %d
less that minimum allowed %d"?

-Toke