From: Georgios Amanakis <gamanakis@gmail.com>
To: Cake List <cake@lists.bufferbloat.net>
Subject: Re: [Cake] dual-src/dsthost unfairness, only with bi-directional traffic
Date: Tue, 15 Jan 2019 17:42:41 -0500 [thread overview]
Message-ID: <CACvFP_ge0L4suK8zvMec=eYTMfEbqp2siHh_JKAK6vgeJUAQew@mail.gmail.com> (raw)
In-Reply-To: <20190115192200.5644-1-gamanakis@gmail.com>
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The patch I previously sent had the host_load manipulated only when
dual-dsthost is sent, since that was what I was primarily testing. For
dual-srchost to behave the same way line 2107 has to be changed, too. Will
resubmit in case anybody wants to test, later today.
On Tue, Jan 15, 2019, 2:22 PM George Amanakis <gamanakis@gmail.com wrote:
>
> I think what is happening here is that if a client has flows such as "a
> (bulk upload)" and "b (bulk download)", the incoming ACKs of flow "a"
> compete with the incoming bulk traffic on flow "b". With compete I mean
> in terms of flow selection.
>
> So if we adjust the host_load to be the same with the bulk_flow_count of
> *each* host, the problem seems to be resolved.
> I drafted a patch below.
>
> Pete's setup, tested with the patch (ingress in mbit/s):
> IP1: 8down 49.18mbit/s
> IP1: 1up 46.73mbit/s
> IP2: 1down 47.39mbit/s
> IP2: 8up 49.21mbit/s
>
>
> ---
> sch_cake.c | 34 ++++++++++++++++++++++++++++------
> 1 file changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/sch_cake.c b/sch_cake.c
> index d434ae0..5c0f0e1 100644
> --- a/sch_cake.c
> +++ b/sch_cake.c
> @@ -148,6 +148,7 @@ struct cake_host {
> u32 dsthost_tag;
> u16 srchost_refcnt;
> u16 dsthost_refcnt;
> + u16 bulk_flow_count;
> };
>
> struct cake_heap_entry {
> @@ -1897,10 +1898,10 @@ static s32 cake_enqueue(struct sk_buff *skb,
> struct Qdisc *sch,
> q->last_packet_time = now;
> }
>
> + struct cake_host *srchost = &b->hosts[flow->srchost];
> + struct cake_host *dsthost = &b->hosts[flow->dsthost];
> /* flowchain */
> if (!flow->set || flow->set == CAKE_SET_DECAYING) {
> - struct cake_host *srchost = &b->hosts[flow->srchost];
> - struct cake_host *dsthost = &b->hosts[flow->dsthost];
> u16 host_load = 1;
>
> if (!flow->set) {
> @@ -1927,6 +1928,11 @@ static s32 cake_enqueue(struct sk_buff *skb, struct
> Qdisc *sch,
> flow->set = CAKE_SET_BULK;
> b->sparse_flow_count--;
> b->bulk_flow_count++;
> + if (cake_dsrc(q->flow_mode))
> + srchost->bulk_flow_count++;
> +
> + if (cake_ddst(q->flow_mode))
> + dsthost->bulk_flow_count++;
> }
>
> if (q->buffer_used > q->buffer_max_used)
> @@ -2101,7 +2107,7 @@ retry:
> host_load = max(host_load, srchost->srchost_refcnt);
>
> if (cake_ddst(q->flow_mode))
> - host_load = max(host_load, dsthost->dsthost_refcnt);
> + host_load = max(host_load, dsthost->bulk_flow_count);
>
> WARN_ON(host_load > CAKE_QUEUES);
>
> @@ -2110,8 +2116,6 @@ retry:
> /* The shifted prandom_u32() is a way to apply dithering to
> * avoid accumulating roundoff errors
> */
> - flow->deficit += (b->flow_quantum * quantum_div[host_load]
> +
> - (prandom_u32() >> 16)) >> 16;
> list_move_tail(&flow->flowchain, &b->old_flows);
>
> /* Keep all flows with deficits out of the sparse and
> decaying
> @@ -2122,6 +2126,11 @@ retry:
> if (flow->head) {
> b->sparse_flow_count--;
> b->bulk_flow_count++;
> + if (cake_dsrc(q->flow_mode))
> + srchost->bulk_flow_count++;
> +
> + if (cake_ddst(q->flow_mode))
> + dsthost->bulk_flow_count++;
> flow->set = CAKE_SET_BULK;
> } else {
> /* we've moved it to the bulk rotation for
> @@ -2131,6 +2140,8 @@ retry:
> flow->set = CAKE_SET_SPARSE_WAIT;
> }
> }
> + flow->deficit += (b->flow_quantum * quantum_div[host_load]
> +
> + (prandom_u32() >> 16)) >> 16;
> goto retry;
> }
>
> @@ -2151,6 +2162,11 @@ retry:
> &b->decaying_flows);
> if (flow->set == CAKE_SET_BULK) {
> b->bulk_flow_count--;
> + if (cake_dsrc(q->flow_mode))
> + srchost->bulk_flow_count--;
> +
> + if (cake_ddst(q->flow_mode))
> + dsthost->bulk_flow_count--;
> b->decaying_flow_count++;
> } else if (flow->set == CAKE_SET_SPARSE ||
> flow->set ==
> CAKE_SET_SPARSE_WAIT) {
> @@ -2164,8 +2180,14 @@ retry:
> if (flow->set == CAKE_SET_SPARSE ||
> flow->set == CAKE_SET_SPARSE_WAIT)
> b->sparse_flow_count--;
> - else if (flow->set == CAKE_SET_BULK)
> + else if (flow->set == CAKE_SET_BULK) {
> b->bulk_flow_count--;
> + if (cake_dsrc(q->flow_mode))
> + srchost->bulk_flow_count--;
> +
> + if (cake_ddst(q->flow_mode))
> + dsthost->bulk_flow_count--;
> + }
> else
> b->decaying_flow_count--;
>
> --
> 2.20.1
>
>
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next prev parent reply other threads:[~2019-01-15 22:42 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-01 23:04 Pete Heist
2019-01-03 3:57 ` Georgios Amanakis
2019-01-03 4:15 ` Georgios Amanakis
2019-01-03 5:18 ` Jonathan Morton
2019-01-03 10:46 ` Pete Heist
2019-01-03 11:03 ` Toke Høiland-Jørgensen
2019-01-03 13:02 ` Pete Heist
2019-01-03 13:20 ` Toke Høiland-Jørgensen
2019-01-03 16:35 ` Pete Heist
2019-01-03 18:24 ` Georgios Amanakis
2019-01-03 22:06 ` Pete Heist
2019-01-04 2:08 ` Georgios Amanakis
2019-01-04 8:09 ` Pete Heist
2019-01-04 7:37 ` Pete Heist
2019-01-04 11:34 ` Pete Heist
2019-01-15 19:22 ` George Amanakis
2019-01-15 22:42 ` Georgios Amanakis [this message]
2019-01-16 3:34 ` George Amanakis
2019-01-16 3:47 ` gamanakis
2019-01-16 7:58 ` Pete Heist
2019-01-26 7:35 ` Pete Heist
2019-01-28 1:34 ` Georgios Amanakis
2019-01-18 10:06 ` Toke Høiland-Jørgensen
2019-01-18 12:07 ` Georgios Amanakis
2019-01-18 13:33 ` Toke Høiland-Jørgensen
2019-01-18 13:40 ` Sebastian Moeller
2019-01-18 14:30 ` Toke Høiland-Jørgensen
2019-01-18 13:45 ` Jonathan Morton
2019-01-18 14:32 ` Toke Høiland-Jørgensen
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