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net/sched: Add support for HW offloading for CBS
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This adds support for offloading the CBS algorithm to the controller,
if supported. Drivers wanting to support CBS offload must implement
the .ndo_setup_tc callback and handle the TC_SETUP_CBS (introduced
here) type.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Henrik Austad <henrik@austad.us>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
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Vinicius Costa Gomes authored and Jeff Kirsher committed Oct 27, 2017
1 parent 585d763 commit 3d0bd02
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Showing 3 changed files with 102 additions and 12 deletions.
1 change: 1 addition & 0 deletions include/linux/netdevice.h
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Original file line number Diff line number Diff line change
Expand Up @@ -776,6 +776,7 @@ enum tc_setup_type {
TC_SETUP_CLSMATCHALL,
TC_SETUP_CLSBPF,
TC_SETUP_BLOCK,
TC_SETUP_CBS,
};

/* These structures hold the attributes of xdp state that are being passed
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9 changes: 9 additions & 0 deletions include/net/pkt_sched.h
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Original file line number Diff line number Diff line change
Expand Up @@ -140,4 +140,13 @@ static inline struct net *qdisc_net(struct Qdisc *q)
return dev_net(q->dev_queue->dev);
}

struct tc_cbs_qopt_offload {
u8 enable;
s32 queue;
s32 hicredit;
s32 locredit;
s32 idleslope;
s32 sendslope;
};

#endif
104 changes: 92 additions & 12 deletions net/sched/sch_cbs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,8 @@
#define BYTES_PER_KBIT (1000LL / 8)

struct cbs_sched_data {
bool offload;
int queue;
s64 port_rate; /* in bytes/s */
s64 last; /* timestamp in ns */
s64 credits; /* in bytes */
Expand All @@ -80,6 +82,11 @@ struct cbs_sched_data {
struct sk_buff *(*dequeue)(struct Qdisc *sch);
};

static int cbs_enqueue_offload(struct sk_buff *skb, struct Qdisc *sch)
{
return qdisc_enqueue_tail(skb, sch);
}

static int cbs_enqueue_soft(struct sk_buff *skb, struct Qdisc *sch)
{
struct cbs_sched_data *q = qdisc_priv(sch);
Expand Down Expand Up @@ -169,6 +176,11 @@ static struct sk_buff *cbs_dequeue_soft(struct Qdisc *sch)
return skb;
}

static struct sk_buff *cbs_dequeue_offload(struct Qdisc *sch)
{
return qdisc_dequeue_head(sch);
}

static struct sk_buff *cbs_dequeue(struct Qdisc *sch)
{
struct cbs_sched_data *q = qdisc_priv(sch);
Expand All @@ -180,14 +192,66 @@ static const struct nla_policy cbs_policy[TCA_CBS_MAX + 1] = {
[TCA_CBS_PARMS] = { .len = sizeof(struct tc_cbs_qopt) },
};

static void cbs_disable_offload(struct net_device *dev,
struct cbs_sched_data *q)
{
struct tc_cbs_qopt_offload cbs = { };
const struct net_device_ops *ops;
int err;

if (!q->offload)
return;

q->enqueue = cbs_enqueue_soft;
q->dequeue = cbs_dequeue_soft;

ops = dev->netdev_ops;
if (!ops->ndo_setup_tc)
return;

cbs.queue = q->queue;
cbs.enable = 0;

err = ops->ndo_setup_tc(dev, TC_SETUP_CBS, &cbs);
if (err < 0)
pr_warn("Couldn't disable CBS offload for queue %d\n",
cbs.queue);
}

static int cbs_enable_offload(struct net_device *dev, struct cbs_sched_data *q,
const struct tc_cbs_qopt *opt)
{
const struct net_device_ops *ops = dev->netdev_ops;
struct tc_cbs_qopt_offload cbs = { };
int err;

if (!ops->ndo_setup_tc)
return -EOPNOTSUPP;

cbs.queue = q->queue;

cbs.enable = 1;
cbs.hicredit = opt->hicredit;
cbs.locredit = opt->locredit;
cbs.idleslope = opt->idleslope;
cbs.sendslope = opt->sendslope;

err = ops->ndo_setup_tc(dev, TC_SETUP_CBS, &cbs);
if (err < 0)
return err;

q->enqueue = cbs_enqueue_offload;
q->dequeue = cbs_dequeue_offload;

return 0;
}

static int cbs_change(struct Qdisc *sch, struct nlattr *opt)
{
struct cbs_sched_data *q = qdisc_priv(sch);
struct net_device *dev = qdisc_dev(sch);
struct nlattr *tb[TCA_CBS_MAX + 1];
struct ethtool_link_ksettings ecmd;
struct tc_cbs_qopt *qopt;
s64 link_speed;
int err;

err = nla_parse_nested(tb, TCA_CBS_MAX, opt, cbs_policy, NULL);
Expand All @@ -199,34 +263,47 @@ static int cbs_change(struct Qdisc *sch, struct nlattr *opt)

qopt = nla_data(tb[TCA_CBS_PARMS]);

if (qopt->offload)
return -EOPNOTSUPP;
if (!qopt->offload) {
struct ethtool_link_ksettings ecmd;
s64 link_speed;

if (!__ethtool_get_link_ksettings(dev, &ecmd))
link_speed = ecmd.base.speed;
else
link_speed = SPEED_1000;
if (!__ethtool_get_link_ksettings(dev, &ecmd))
link_speed = ecmd.base.speed;
else
link_speed = SPEED_1000;

q->port_rate = link_speed * 1000 * BYTES_PER_KBIT;
q->port_rate = link_speed * 1000 * BYTES_PER_KBIT;

q->enqueue = cbs_enqueue_soft;
q->dequeue = cbs_dequeue_soft;
cbs_disable_offload(dev, q);
} else {
err = cbs_enable_offload(dev, q, qopt);
if (err < 0)
return err;
}

/* Everything went OK, save the parameters used. */
q->hicredit = qopt->hicredit;
q->locredit = qopt->locredit;
q->idleslope = qopt->idleslope * BYTES_PER_KBIT;
q->sendslope = qopt->sendslope * BYTES_PER_KBIT;
q->offload = qopt->offload;

return 0;
}

static int cbs_init(struct Qdisc *sch, struct nlattr *opt)
{
struct cbs_sched_data *q = qdisc_priv(sch);
struct net_device *dev = qdisc_dev(sch);

if (!opt)
return -EINVAL;

q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);

q->enqueue = cbs_enqueue_soft;
q->dequeue = cbs_dequeue_soft;

qdisc_watchdog_init(&q->watchdog, sch);

return cbs_change(sch, opt);
Expand All @@ -235,8 +312,11 @@ static int cbs_init(struct Qdisc *sch, struct nlattr *opt)
static void cbs_destroy(struct Qdisc *sch)
{
struct cbs_sched_data *q = qdisc_priv(sch);
struct net_device *dev = qdisc_dev(sch);

qdisc_watchdog_cancel(&q->watchdog);

cbs_disable_offload(dev, q);
}

static int cbs_dump(struct Qdisc *sch, struct sk_buff *skb)
Expand All @@ -253,7 +333,7 @@ static int cbs_dump(struct Qdisc *sch, struct sk_buff *skb)
opt.locredit = q->locredit;
opt.sendslope = div64_s64(q->sendslope, BYTES_PER_KBIT);
opt.idleslope = div64_s64(q->idleslope, BYTES_PER_KBIT);
opt.offload = 0;
opt.offload = q->offload;

if (nla_put(skb, TCA_CBS_PARMS, sizeof(opt), &opt))
goto nla_put_failure;
Expand Down

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