[Cerowrt-devel] Fwd: [PATCH net-next] net_sched: restore "mpu xxx" handling

[Sebastian Moeller]

No idea, sqm-scripts long had supported htb's linklayer accounting but defaulted to using tc stab instead, and mainly for htb+fq_codel, for cake it defaulted to cake's internal accounting.

I have no recollection when I last tested that, probably when I was still on an ADSL link without a relevant mpu.... 

Regards
        Sebastian



On 13 January 2022 00:08:10 CET, Dave Taht <dave.taht at gmail.com> wrote:
>this has been broken this long??
>
>---------- Forwarded message ---------
>From: Kevin Bracey <kevin at bracey.fi>
>Date: Fri, Jan 7, 2022 at 4:56 PM
>Subject: [PATCH net-next] net_sched: restore "mpu xxx" handling
>To: <netdev at vger.kernel.org>
>Cc: Kevin Bracey <kevin at bracey.fi>, Eric Dumazet
><edumazet at google.com>, Jiri Pirko <jiri at resnulli.us>, Vimalkumar
><j.vimal at gmail.com>
>
>
>commit 56b765b79e9a ("htb: improved accuracy at high rates") broke
>"overhead X", "linklayer atm" and "mpu X" attributes.
>
>"overhead X" and "linklayer atm" have already been fixed. This restores
>the "mpu X" handling, as might be used by DOCSIS or Ethernet shaping:
>
>    tc class add ... htb rate X overhead 4 mpu 64
>
>The code being fixed is used by htb, tbf and act_police. Cake has its
>own mpu handling. qdisc_calculate_pkt_len still uses the size table
>containing values adjusted for mpu by user space.
>
>Fixes: 56b765b79e9a ("htb: improved accuracy at high rates")
>Signed-off-by: Kevin Bracey <kevin at bracey.fi>
>Cc: Eric Dumazet <edumazet at google.com>
>Cc: Jiri Pirko <jiri at resnulli.us>
>Cc: Vimalkumar <j.vimal at gmail.com>
>---
> include/net/sch_generic.h | 5 +++++
> net/sched/sch_generic.c   | 1 +
> 2 files changed, 6 insertions(+)
>
>diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
>index c70e6d2b2fdd..fddca0aa73ef 100644
>--- a/include/net/sch_generic.h
>+++ b/include/net/sch_generic.h
>@@ -1244,6 +1244,7 @@ struct psched_ratecfg {
>        u64     rate_bytes_ps; /* bytes per second */
>        u32     mult;
>        u16     overhead;
>+       u16     mpu;
>        u8      linklayer;
>        u8      shift;
> };
>@@ -1253,6 +1254,9 @@ static inline u64 psched_l2t_ns(const struct
>psched_ratecfg *r,
> {
>        len += r->overhead;
>
>+       if (len < r->mpu)
>+               len = r->mpu;
>+
>        if (unlikely(r->linklayer == TC_LINKLAYER_ATM))
>                return ((u64)(DIV_ROUND_UP(len,48)*53) * r->mult) >> r->shift;
>
>@@ -1275,6 +1279,7 @@ static inline void psched_ratecfg_getrate(struct
>tc_ratespec *res,
>        res->rate = min_t(u64, r->rate_bytes_ps, ~0U);
>
>        res->overhead = r->overhead;
>+       res->mpu = r->mpu;
>        res->linklayer = (r->linklayer & TC_LINKLAYER_MASK);
> }
>
>diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
>index 3b0f62095803..5d391fe3137d 100644
>--- a/net/sched/sch_generic.c
>+++ b/net/sched/sch_generic.c
>@@ -1474,6 +1474,7 @@ void psched_ratecfg_precompute(struct psched_ratecfg *r,
> {
>        memset(r, 0, sizeof(*r));
>        r->overhead = conf->overhead;
>+       r->mpu = conf->mpu;
>        r->rate_bytes_ps = max_t(u64, conf->rate, rate64);
>        r->linklayer = (conf->linklayer & TC_LINKLAYER_MASK);
>        psched_ratecfg_precompute__(r->rate_bytes_ps, &r->mult, &r->shift);
>--
>2.25.1
>
>
>
>-- 
>I tried to build a better future, a few times:
>https://wayforward.archive.org/?site=https%3A%2F%2Fwww.icei.org
>
>Dave Täht CEO, TekLibre, LLC
>_______________________________________________
>Cerowrt-devel mailing list
>Cerowrt-devel at lists.bufferbloat.net
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-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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