sfc: Implement adaptive IRQ moderation
Calculate a score for each 1000 IRQs:
- TX completions are worth 1 point
- RX completions are worth 4 if merged using LRO or 2 otherwise
Reduce moderation if the score is less than 10000, down to a minimum
of 5 us. Increase moderation if the score is more than 20000, up to
the specified maximum.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/sfc/falcon.c b/drivers/net/sfc/falcon.c
index f42fc60..23a1b14 100644
--- a/drivers/net/sfc/falcon.c
+++ b/drivers/net/sfc/falcon.c
@@ -729,6 +729,9 @@
tx_ev_desc_ptr = EFX_QWORD_FIELD(*event, TX_EV_DESC_PTR);
tx_ev_q_label = EFX_QWORD_FIELD(*event, TX_EV_Q_LABEL);
tx_queue = &efx->tx_queue[tx_ev_q_label];
+ channel->irq_mod_score +=
+ (tx_ev_desc_ptr - tx_queue->read_count) &
+ efx->type->txd_ring_mask;
efx_xmit_done(tx_queue, tx_ev_desc_ptr);
} else if (EFX_QWORD_FIELD(*event, TX_EV_WQ_FF_FULL)) {
/* Rewrite the FIFO write pointer */
@@ -898,6 +901,8 @@
discard = true;
}
+ channel->irq_mod_score += 2;
+
/* Handle received packet */
efx_rx_packet(rx_queue, rx_ev_desc_ptr, rx_ev_byte_cnt,
checksummed, discard);
@@ -1075,14 +1080,15 @@
* program is based at 0. So actual interrupt moderation
* achieved is ((x + 1) * res).
*/
- unsigned int res = 5;
- channel->irq_moderation -= (channel->irq_moderation % res);
- if (channel->irq_moderation < res)
- channel->irq_moderation = res;
+ channel->irq_moderation -= (channel->irq_moderation %
+ FALCON_IRQ_MOD_RESOLUTION);
+ if (channel->irq_moderation < FALCON_IRQ_MOD_RESOLUTION)
+ channel->irq_moderation = FALCON_IRQ_MOD_RESOLUTION;
EFX_POPULATE_DWORD_2(timer_cmd,
TIMER_MODE, TIMER_MODE_INT_HLDOFF,
TIMER_VAL,
- (channel->irq_moderation / res) - 1);
+ channel->irq_moderation /
+ FALCON_IRQ_MOD_RESOLUTION - 1);
} else {
EFX_POPULATE_DWORD_2(timer_cmd,
TIMER_MODE, TIMER_MODE_DIS,