Commit 364b6055 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: busy-poll: return busypolling status to drivers 



NAPI drivers use napi_complete_done() or napi_complete() when
they drained RX ring and right before re-enabling device interrupts.

In busy polling, we can avoid interrupts being delivered since
we are polling RX ring in a controlled loop.

Drivers can chose to use napi_complete_done() return value
to reduce interrupts overhead while busy polling is active.

This is optional, legacy drivers should work fine even
if not updated.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Adam Belay <abelay@google.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Cc: Yuval Mintz <Yuval.Mintz@cavium.com>
Cc: Ariel Elior <ariel.elior@cavium.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 21cb84c4

include/linux/netdevice.h

+4 −3
Original line number Diff line number Diff line
@@ -463,16 +463,17 @@ static inline bool napi_reschedule(struct napi_struct *napi) 
	return false;

}



void __napi_complete(struct napi_struct *n);

void napi_complete_done(struct napi_struct *n, int work_done);

bool __napi_complete(struct napi_struct *n);

bool napi_complete_done(struct napi_struct *n, int work_done);

/**

 *	napi_complete - NAPI processing complete

 *	@n: NAPI context

 *

 * Mark NAPI processing as complete.

 * Consider using napi_complete_done() instead.

 * Return false if device should avoid rearming interrupts.

 */

static inline void napi_complete(struct napi_struct *n)

static inline bool napi_complete(struct napi_struct *n)

{

	return napi_complete_done(n, 0);

}

net/core/dev.c

+6 −4
Original line number Diff line number Diff line
@@ -4898,7 +4898,7 @@ void __napi_schedule_irqoff(struct napi_struct *n) 
}

EXPORT_SYMBOL(__napi_schedule_irqoff);



void __napi_complete(struct napi_struct *n)

bool __napi_complete(struct napi_struct *n)

{

	BUG_ON(!test_bit(NAPI_STATE_SCHED, &n->state));
@@ -4906,15 +4906,16 @@ void __napi_complete(struct napi_struct *n) 
	 * napi_complete_done().

	 */

	if (unlikely(test_bit(NAPI_STATE_IN_BUSY_POLL, &n->state)))

		return;

		return false;



	list_del_init(&n->poll_list);

	smp_mb__before_atomic();

	clear_bit(NAPI_STATE_SCHED, &n->state);

	return true;

}

EXPORT_SYMBOL(__napi_complete);



void napi_complete_done(struct napi_struct *n, int work_done)

bool napi_complete_done(struct napi_struct *n, int work_done)

{

	unsigned long flags;
@@ -4926,7 +4927,7 @@ void napi_complete_done(struct napi_struct *n, int work_done) 
	 */

	if (unlikely(n->state & (NAPIF_STATE_NPSVC |

				 NAPIF_STATE_IN_BUSY_POLL)))

		return;

		return false;



	if (n->gro_list) {

		unsigned long timeout = 0;
@@ -4948,6 +4949,7 @@ void napi_complete_done(struct napi_struct *n, int work_done) 
		__napi_complete(n);

		local_irq_restore(flags);

	}

	return true;

}

EXPORT_SYMBOL(napi_complete_done);

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