Commit dfcb63ce authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Jakub Kicinski
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fq_codel: generalise ce_threshold marking for subset of traffic 



Commit e72aeb9e ("fq_codel: implement L4S style ce_threshold_ect1
marking") expanded the ce_threshold feature of FQ-CoDel so it can
be applied to a subset of the traffic, using the ECT(1) bit of the ECN
field as the classifier. However, hard-coding ECT(1) as the only
classifier for this feature seems limiting, so let's expand it to be more
general.

To this end, change the parameter from a ce_threshold_ect1 boolean, to a
one-byte selector/mask pair (ce_threshold_{selector,mask}) which is applied
to the whole diffserv/ECN field in the IP header. This makes it possible to
classify packets by any value in either the ECN field or the diffserv
field. In particular, setting a selector of INET_ECN_ECT_1 and a mask of
INET_ECN_MASK corresponds to the functionality before this patch, and a
mask of ~INET_ECN_MASK allows using the selector as a straight-forward
match against a diffserv code point:

 # apply ce_threshold to ECT(1) traffic
 tc qdisc replace dev eth0 root fq_codel ce_threshold 1ms ce_threshold_selector 0x1/0x3

 # apply ce_threshold to ECN-capable traffic marked as diffserv AF22
 tc qdisc replace dev eth0 root fq_codel ce_threshold 1ms ce_threshold_selector 0x50/0xfc

Regardless of the selector chosen, the normal rules for ECN-marking of
packets still apply, i.e., the flow must still declare itself ECN-capable
by setting one of the bits in the ECN field to get marked at all.

v2:
- Add tc usage examples to patch description

Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20211019174709.69081-1-toke@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 2641b62d

include/net/codel.h

+5 −2
Original line number Original line Diff line number Diff line
@@ -102,7 +102,9 @@ static inline u32 codel_time_to_us(codel_time_t val) 
 * @interval:	width of moving time window

 * @interval:	width of moving time window

 * @mtu:	device mtu, or minimal queue backlog in bytes.

 * @mtu:	device mtu, or minimal queue backlog in bytes.

 * @ecn:	is Explicit Congestion Notification enabled

 * @ecn:	is Explicit Congestion Notification enabled

 * @ce_threshold_ect1: if ce_threshold only marks ECT(1) packets

 * @ce_threshold_selector: apply ce_threshold to packets matching this value

 *                         in the diffserv/ECN byte of the IP header

 * @ce_threshold_mask: mask to apply to ce_threshold_selector comparison

 */

 */

struct codel_params {

struct codel_params {

	codel_time_t	target;

	codel_time_t	target;
@@ -110,7 +112,8 @@ struct codel_params { 
	codel_time_t	interval;

	codel_time_t	interval;

	u32		mtu;

	u32		mtu;

	bool		ecn;

	bool		ecn;

	bool		ce_threshold_ect1;

	u8		ce_threshold_selector;

	u8		ce_threshold_mask;

};

};





/**

/**

include/net/codel_impl.h

+7 −7
Original line number Original line Diff line number Diff line
@@ -54,7 +54,8 @@ static void codel_params_init(struct codel_params *params) 
	params->interval = MS2TIME(100);

	params->interval = MS2TIME(100);

	params->target = MS2TIME(5);

	params->target = MS2TIME(5);

	params->ce_threshold = CODEL_DISABLED_THRESHOLD;

	params->ce_threshold = CODEL_DISABLED_THRESHOLD;

	params->ce_threshold_ect1 = false;

	params->ce_threshold_mask = 0;

	params->ce_threshold_selector = 0;

	params->ecn = false;

	params->ecn = false;

}

}
@@ -250,13 +251,12 @@ static struct sk_buff *codel_dequeue(void *ctx, 
	if (skb && codel_time_after(vars->ldelay, params->ce_threshold)) {

	if (skb && codel_time_after(vars->ldelay, params->ce_threshold)) {

		bool set_ce = true;

		bool set_ce = true;





		if (params->ce_threshold_ect1) {

		if (params->ce_threshold_mask) {

			/* Note: if skb_get_dsfield() returns -1, following

			int dsfield = skb_get_dsfield(skb);

			 * gives INET_ECN_MASK, which is != INET_ECN_ECT_1.

			 */

			u8 ecn = skb_get_dsfield(skb) & INET_ECN_MASK;





			set_ce = (ecn == INET_ECN_ECT_1);

			set_ce = (dsfield >= 0 &&

				  (((u8)dsfield & params->ce_threshold_mask) ==

				   params->ce_threshold_selector));

		}

		}

		if (set_ce && INET_ECN_set_ce(skb))

		if (set_ce && INET_ECN_set_ce(skb))

			stats->ce_mark++;

			stats->ce_mark++;

include/uapi/linux/pkt_sched.h

+2 −1
Original line number Original line Diff line number Diff line
@@ -840,7 +840,8 @@ enum { 
	TCA_FQ_CODEL_CE_THRESHOLD,

	TCA_FQ_CODEL_CE_THRESHOLD,

	TCA_FQ_CODEL_DROP_BATCH_SIZE,

	TCA_FQ_CODEL_DROP_BATCH_SIZE,

	TCA_FQ_CODEL_MEMORY_LIMIT,

	TCA_FQ_CODEL_MEMORY_LIMIT,

	TCA_FQ_CODEL_CE_THRESHOLD_ECT1,

	TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR,

	TCA_FQ_CODEL_CE_THRESHOLD_MASK,

	__TCA_FQ_CODEL_MAX

	__TCA_FQ_CODEL_MAX

};

};

net/mac80211/sta_info.c

+2 −1
Original line number Original line Diff line number Diff line
@@ -513,7 +513,8 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata, 
	sta->cparams.target = MS2TIME(20);

	sta->cparams.target = MS2TIME(20);

	sta->cparams.interval = MS2TIME(100);

	sta->cparams.interval = MS2TIME(100);

	sta->cparams.ecn = true;

	sta->cparams.ecn = true;

	sta->cparams.ce_threshold_ect1 = false;

	sta->cparams.ce_threshold_selector = 0;

	sta->cparams.ce_threshold_mask = 0;





	sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr);

	sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr);

net/sched/sch_fq_codel.c

+9 −4
Original line number Original line Diff line number Diff line
@@ -362,7 +362,8 @@ static const struct nla_policy fq_codel_policy[TCA_FQ_CODEL_MAX + 1] = { 
	[TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },

	[TCA_FQ_CODEL_CE_THRESHOLD] = { .type = NLA_U32 },

	[TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },

	[TCA_FQ_CODEL_DROP_BATCH_SIZE] = { .type = NLA_U32 },

	[TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },

	[TCA_FQ_CODEL_MEMORY_LIMIT] = { .type = NLA_U32 },

	[TCA_FQ_CODEL_CE_THRESHOLD_ECT1] = { .type = NLA_U8 },

	[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR] = { .type = NLA_U8 },

	[TCA_FQ_CODEL_CE_THRESHOLD_MASK] = { .type = NLA_U8 },

};

};





static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,

static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
@@ -409,8 +410,10 @@ static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt, 
		q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;

		q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;

	}

	}





	if (tb[TCA_FQ_CODEL_CE_THRESHOLD_ECT1])

	if (tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR])

		q->cparams.ce_threshold_ect1 = !!nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_ECT1]);

		q->cparams.ce_threshold_selector = nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR]);

	if (tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK])

		q->cparams.ce_threshold_mask = nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK]);





	if (tb[TCA_FQ_CODEL_INTERVAL]) {

	if (tb[TCA_FQ_CODEL_INTERVAL]) {

		u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);

		u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
@@ -552,7 +555,9 @@ static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb) 
		if (nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,

		if (nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,

				codel_time_to_us(q->cparams.ce_threshold)))

				codel_time_to_us(q->cparams.ce_threshold)))

			goto nla_put_failure;

			goto nla_put_failure;

		if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_ECT1, q->cparams.ce_threshold_ect1))

		if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR, q->cparams.ce_threshold_selector))

			goto nla_put_failure;

		if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_MASK, q->cparams.ce_threshold_mask))

			goto nla_put_failure;

			goto nla_put_failure;

	}

	}