Commit f858cc9e authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net: add IFLA_MAX_PACING_OFFLOAD_HORIZON device attribute 

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: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20241003121219.2396589-2-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 3d07b691

Documentation/netlink/specs/rt_link.yaml

+4 −0
Original line number Diff line number Diff line
@@ -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:

Documentation/networking/net_cachelines/net_device.rst

+1 −0
Original line number Diff line number Diff line
@@ -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

include/linux/netdevice.h

+4 −0
Original line number Diff line number Diff line
@@ -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;

include/uapi/linux/if_link.h

+1 −0
Original line number Diff line number Diff line
@@ -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

};

net/core/rtnetlink.c

+4 −0
Original line number Diff line number Diff line
@@ -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 },