From: Petr Machata <petrm@mellanox.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Ido Schimmel <idosch@idosch.org>,
netdev@vger.kernel.org, davem@davemloft.net, jiri@mellanox.com,
jhs@mojatatu.com, xiyou.wangcong@gmail.com, mlxsw@mellanox.com,
Ido Schimmel <idosch@mellanox.com>
Subject: Re: [PATCH net-next 3/6] net: sched: RED: Introduce an ECN tail-dropping mode
Date: Tue, 10 Mar 2020 10:48:17 +0100 [thread overview]
Message-ID: <87tv2wy1zy.fsf@mellanox.com> (raw)
In-Reply-To: <20200309151255.29bb3a4b@kicinski-fedora-PC1C0HJN>
Jakub Kicinski <kuba@kernel.org> writes:
> On Mon, 9 Mar 2020 20:35:00 +0200 Ido Schimmel wrote:
>> diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
>> index f9839d68b811..d72db7643a37 100644
>> --- a/net/sched/sch_red.c
>> +++ b/net/sched/sch_red.c
>> @@ -44,7 +44,8 @@ struct red_sched_data {
>> struct Qdisc *qdisc;
>> };
>>
>> -#define RED_SUPPORTED_FLAGS (TC_RED_ECN | TC_RED_HARDDROP | TC_RED_ADAPTATIVE)
>> +#define RED_SUPPORTED_FLAGS (TC_RED_ECN | TC_RED_HARDDROP | \
>> + TC_RED_ADAPTATIVE | TC_RED_TAILDROP)
>>
>> static inline int red_use_ecn(struct red_sched_data *q)
>> {
>> @@ -56,6 +57,11 @@ static inline int red_use_harddrop(struct red_sched_data *q)
>> return q->flags & TC_RED_HARDDROP;
>> }
>>
>> +static inline int red_use_taildrop(struct red_sched_data *q)
>
> Please don't do static inlines in C code, even if the neighboring code
> does.
Ok.
>> +{
>> + return q->flags & TC_RED_TAILDROP;
>> +}
>> +
>> static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch,
>> struct sk_buff **to_free)
>> {
>> @@ -76,23 +82,36 @@ static int red_enqueue(struct sk_buff *skb, struct Qdisc *sch,
>>
>> case RED_PROB_MARK:
>> qdisc_qstats_overlimit(sch);
>> - if (!red_use_ecn(q) || !INET_ECN_set_ce(skb)) {
>> + if (!red_use_ecn(q)) {
>> q->stats.prob_drop++;
>> goto congestion_drop;
>> }
>>
>> - q->stats.prob_mark++;
>> + if (INET_ECN_set_ce(skb)) {
>> + q->stats.prob_mark++;
>> + } else if (red_use_taildrop(q)) {
>
> This condition is inverted, no?
>
> If user requested taildrop the packet should be queued.
Argh, yes! I was meddling with different ways of coding the if-else
after Ido reviewed it and screwed it up. Thanks for catching it.
My tests have not caught this, because they all hit the hard mark case
:(
>> + q->stats.prob_drop++;
>> + goto congestion_drop;
>> + }
>> +
>> + /* Non-ECT packet in ECN taildrop mode: queue it. */
>> break;
>>
>> case RED_HARD_MARK:
>> qdisc_qstats_overlimit(sch);
>> - if (red_use_harddrop(q) || !red_use_ecn(q) ||
>> - !INET_ECN_set_ce(skb)) {
>> + if (red_use_harddrop(q) || !red_use_ecn(q)) {
>> + q->stats.forced_drop++;
>> + goto congestion_drop;
>> + }
>> +
>> + if (INET_ECN_set_ce(skb)) {
>> + q->stats.forced_mark++;
>> + } else if (!red_use_taildrop(q)) {
>
> This one looks correct.
>
>> q->stats.forced_drop++;
>> goto congestion_drop;
>> }
>>
>> - q->stats.forced_mark++;
>> + /* Non-ECT packet in ECN taildrop mode: queue it. */
>> break;
>> }
>>
next prev parent reply other threads:[~2020-03-10 9:48 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-09 18:34 [PATCH net-next 0/6] RED: Introduce an ECN tail-dropping mode Ido Schimmel
2020-03-09 18:34 ` [PATCH net-next 1/6] selftests: qdiscs: Add TDC test for RED Ido Schimmel
2020-03-10 15:40 ` Roman Mashak
2020-03-10 16:56 ` Petr Machata
2020-03-10 17:28 ` Roman Mashak
2020-03-09 18:34 ` [PATCH net-next 2/6] net: sched: Add centralized RED flag checking Ido Schimmel
2020-03-09 22:18 ` Jakub Kicinski
2020-03-10 9:48 ` Petr Machata
2020-03-10 19:53 ` Jakub Kicinski
2020-03-10 22:23 ` Petr Machata
2020-03-10 23:00 ` Jakub Kicinski
2020-03-10 23:53 ` Petr Machata
2020-03-09 18:35 ` [PATCH net-next 3/6] net: sched: RED: Introduce an ECN tail-dropping mode Ido Schimmel
2020-03-09 22:12 ` Jakub Kicinski
2020-03-10 9:48 ` Petr Machata [this message]
2020-03-09 18:35 ` [PATCH net-next 4/6] mlxsw: spectrum_qdisc: Offload RED " Ido Schimmel
2020-03-09 18:35 ` [PATCH net-next 5/6] selftests: qdiscs: RED: Add taildrop tests Ido Schimmel
2020-03-09 18:35 ` [PATCH net-next 6/6] selftests: mlxsw: RED: Test RED ECN taildrop offload Ido Schimmel
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