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net: add IFLA_MAX_PACING_OFFLOAD_HORIZON device attribute

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Some network devices have the ability to offload EDT (Earliest
Departure Time) which is the model used for TCP pacing and FQ
packet scheduler.

Some of them implement the timing wheel mechanism described in
https://saeed.github.io/files/carousel-sigcomm17.pdf
with an associated 'timing wheel horizon'.

This patch adds dev->max_pacing_offload_horizon expressing
this timing wheel horizon in nsec units.

This is a read-only attribute.

Unless a driver sets it, dev->max_pacing_offload_horizon
is zero.

v2: addressed Jakub feedback ( https://lore.kernel.org/netdev/20240930152304.472767-2-edumazet@google.com/T/#mf6294d714c41cc459962154cc2580ce3c9693663 )
v3: added yaml doc (also per Jakub feedback)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20241003121219.2396589-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-10-03 12:12:18 +00:00 committed by Jakub Kicinski
parent 3d07b691ee
commit f858cc9eed
6 changed files with 15 additions and 0 deletions
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4
Documentation/netlink/specs/rt_link.yaml
View File

@ -1137,6 +1137,10 @@ attribute-sets:
name: dpll-pin
type: nest
nested-attributes: link-dpll-pin-attrs
-
name: max-pacing-offload-horizon
type: uint
doc: EDT offload horizon supported by the device (in nsec).
-
name: af-spec-attrs
attributes:

1
Documentation/networking/net_cachelines/net_device.rst
View File

@ -183,3 +183,4 @@ struct_devlink_port* devlink_port
struct_dpll_pin* dpll_pin
struct hlist_head page_pools
struct dim_irq_moder* irq_moder
u64 max_pacing_offload_horizon

4
include/linux/netdevice.h
View File

@ -2009,6 +2009,8 @@ enum netdev_reg_state {
* @dpll_pin: Pointer to the SyncE source pin of a DPLL subsystem,
* where the clock is recovered.
*
* @max_pacing_offload_horizon: max EDT offload horizon in nsec.
*
* FIXME: cleanup struct net_device such that network protocol info
* moves out.
*/
@ -2399,6 +2401,8 @@ struct net_device {
/** @irq_moder: dim parameters used if IS_ENABLED(CONFIG_DIMLIB). */
struct dim_irq_moder *irq_moder;
u64 max_pacing_offload_horizon;
u8 priv[] ____cacheline_aligned
__counted_by(priv_len);
} ____cacheline_aligned;

1
include/uapi/linux/if_link.h
View File

@ -377,6 +377,7 @@ enum {
IFLA_GSO_IPV4_MAX_SIZE,
IFLA_GRO_IPV4_MAX_SIZE,
IFLA_DPLL_PIN,
IFLA_MAX_PACING_OFFLOAD_HORIZON,
__IFLA_MAX
};

4
net/core/rtnetlink.c
View File

@ -1118,6 +1118,7 @@ static noinline size_t if_nlmsg_size(const struct net_device *dev,
+ nla_total_size(MAX_ADDR_LEN) /* IFLA_PERM_ADDRESS */
+ rtnl_devlink_port_size(dev)
+ rtnl_dpll_pin_size(dev)
+ nla_total_size(8) /* IFLA_MAX_PACING_OFFLOAD_HORIZON */
+ 0;
}
@ -1867,6 +1868,8 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
READ_ONCE(dev->tso_max_size)) ||
nla_put_u32(skb, IFLA_TSO_MAX_SEGS,
READ_ONCE(dev->tso_max_segs)) ||
nla_put_uint(skb, IFLA_MAX_PACING_OFFLOAD_HORIZON,
READ_ONCE(dev->max_pacing_offload_horizon)) ||
#ifdef CONFIG_RPS
nla_put_u32(skb, IFLA_NUM_RX_QUEUES,
READ_ONCE(dev->num_rx_queues)) ||
@ -1975,6 +1978,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
}
static const struct nla_policy ifla_policy[IFLA_MAX+1] = {
[IFLA_UNSPEC] = { .strict_start_type = IFLA_DPLL_PIN },
[IFLA_IFNAME] = { .type = NLA_STRING, .len = IFNAMSIZ-1 },
[IFLA_ADDRESS] = { .type = NLA_BINARY, .len = MAX_ADDR_LEN },
[IFLA_BROADCAST] = { .type = NLA_BINARY, .len = MAX_ADDR_LEN },

1
tools/include/uapi/linux/if_link.h
View File

@ -377,6 +377,7 @@ enum {
IFLA_GSO_IPV4_MAX_SIZE,
IFLA_GRO_IPV4_MAX_SIZE,
IFLA_DPLL_PIN,
IFLA_MAX_PACING_OFFLOAD_HORIZON,
__IFLA_MAX
};