Commit 012b7206 authored by David Howells's avatar David Howells Committed by Jakub Kicinski
Browse files

rxrpc: Only transmit one ACK per jumbo packet received 



Only generate one ACK packet for all the subpackets in a jumbo packet.  If
we would like to generate more than one ACK, we prioritise them base on
their reason code, in the order, highest first:

   OutOfSeq > NoSpace > ExceedsWin > Duplicate > Requested > Delay > Idle

For the first four, we reference the lowest offending subpacket; for the
last three, the highest.

This reduces the number of ACKs we end up transmitting to one per UDP
packet transmitted to reduce network loading and packet parsing.

Fixes: 5d7edbc9 ("rxrpc: Get rid of the Rx ring")
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Reviewed-by: default avatarJeffrey Altman &lt;jaltman@auristor.com <mailto:jaltman@auristor.com&gt;>
Link: https://lore.kernel.org/r/20240503150749.1001323-3-dhowells@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent ba4e1038

net/rxrpc/input.c

+35 −11
Original line number Diff line number Diff line
@@ -9,6 +9,17 @@ 


#include "ar-internal.h"



/* Override priority when generating ACKs for received DATA */

static const u8 rxrpc_ack_priority[RXRPC_ACK__INVALID] = {

	[RXRPC_ACK_IDLE]		= 1,

	[RXRPC_ACK_DELAY]		= 2,

	[RXRPC_ACK_REQUESTED]		= 3,

	[RXRPC_ACK_DUPLICATE]		= 4,

	[RXRPC_ACK_EXCEEDS_WINDOW]	= 5,

	[RXRPC_ACK_NOSPACE]		= 6,

	[RXRPC_ACK_OUT_OF_SEQUENCE]	= 7,

};



static void rxrpc_proto_abort(struct rxrpc_call *call, rxrpc_seq_t seq,

			      enum rxrpc_abort_reason why)

{
@@ -365,7 +376,7 @@ static void rxrpc_input_queue_data(struct rxrpc_call *call, struct sk_buff *skb, 
 * Process a DATA packet.

 */

static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb,

				 bool *_notify)

				 bool *_notify, rxrpc_serial_t *_ack_serial, int *_ack_reason)

{

	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);

	struct sk_buff *oos;
@@ -418,8 +429,6 @@ static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb, 
		/* Send an immediate ACK if we fill in a hole */

		else if (!skb_queue_empty(&call->rx_oos_queue))

			ack_reason = RXRPC_ACK_DELAY;

		else

			call->ackr_nr_unacked++;



		window++;

		if (after(window, wtop)) {
@@ -497,12 +506,16 @@ static void rxrpc_input_data_one(struct rxrpc_call *call, struct sk_buff *skb, 
	}



send_ack:

	if (ack_reason >= 0)

		rxrpc_send_ACK(call, ack_reason, serial,

			       rxrpc_propose_ack_input_data);

	else

		rxrpc_propose_delay_ACK(call, serial,

					rxrpc_propose_ack_input_data);

	if (ack_reason >= 0) {

		if (rxrpc_ack_priority[ack_reason] > rxrpc_ack_priority[*_ack_reason]) {

			*_ack_serial = serial;

			*_ack_reason = ack_reason;

		} else if (rxrpc_ack_priority[ack_reason] == rxrpc_ack_priority[*_ack_reason] &&

			   ack_reason == RXRPC_ACK_REQUESTED) {

			*_ack_serial = serial;

			*_ack_reason = ack_reason;

		}

	}

}



/*
@@ -513,9 +526,11 @@ static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb 
	struct rxrpc_jumbo_header jhdr;

	struct rxrpc_skb_priv *sp = rxrpc_skb(skb), *jsp;

	struct sk_buff *jskb;

	rxrpc_serial_t ack_serial = 0;

	unsigned int offset = sizeof(struct rxrpc_wire_header);

	unsigned int len = skb->len - offset;

	bool notify = false;

	int ack_reason = 0;



	while (sp->hdr.flags & RXRPC_JUMBO_PACKET) {

		if (len < RXRPC_JUMBO_SUBPKTLEN)
@@ -535,7 +550,7 @@ static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb 
		jsp = rxrpc_skb(jskb);

		jsp->offset = offset;

		jsp->len = RXRPC_JUMBO_DATALEN;

		rxrpc_input_data_one(call, jskb, &notify);

		rxrpc_input_data_one(call, jskb, &notify, &ack_serial, &ack_reason);

		rxrpc_free_skb(jskb, rxrpc_skb_put_jumbo_subpacket);



		sp->hdr.flags = jhdr.flags;
@@ -548,7 +563,16 @@ static bool rxrpc_input_split_jumbo(struct rxrpc_call *call, struct sk_buff *skb 


	sp->offset = offset;

	sp->len    = len;

	rxrpc_input_data_one(call, skb, &notify);

	rxrpc_input_data_one(call, skb, &notify, &ack_serial, &ack_reason);



	if (ack_reason > 0) {

		rxrpc_send_ACK(call, ack_reason, ack_serial,

			       rxrpc_propose_ack_input_data);

	} else {

		call->ackr_nr_unacked++;

		rxrpc_propose_delay_ACK(call, sp->hdr.serial,

					rxrpc_propose_ack_input_data);

	}

	if (notify) {

		trace_rxrpc_notify_socket(call->debug_id, sp->hdr.serial);

		rxrpc_notify_socket(call);