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/efx.c b/drivers/net/sfc/efx.c
index 8fa68d8..6eff9ca 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -133,6 +133,16 @@
module_param(phy_flash_cfg, int, 0644);
MODULE_PARM_DESC(phy_flash_cfg, "Set PHYs into reflash mode initially");
+static unsigned irq_adapt_low_thresh = 10000;
+module_param(irq_adapt_low_thresh, uint, 0644);
+MODULE_PARM_DESC(irq_adapt_low_thresh,
+ "Threshold score for reducing IRQ moderation");
+
+static unsigned irq_adapt_high_thresh = 20000;
+module_param(irq_adapt_high_thresh, uint, 0644);
+MODULE_PARM_DESC(irq_adapt_high_thresh,
+ "Threshold score for increasing IRQ moderation");
+
/**************************************************************************
*
* Utility functions and prototypes
@@ -223,6 +233,35 @@
rx_packets = efx_process_channel(channel, budget);
if (rx_packets < budget) {
+ struct efx_nic *efx = channel->efx;
+
+ if (channel->used_flags & EFX_USED_BY_RX &&
+ efx->irq_rx_adaptive &&
+ unlikely(++channel->irq_count == 1000)) {
+ unsigned old_irq_moderation = channel->irq_moderation;
+
+ if (unlikely(channel->irq_mod_score <
+ irq_adapt_low_thresh)) {
+ channel->irq_moderation =
+ max_t(int,
+ channel->irq_moderation -
+ FALCON_IRQ_MOD_RESOLUTION,
+ FALCON_IRQ_MOD_RESOLUTION);
+ } else if (unlikely(channel->irq_mod_score >
+ irq_adapt_high_thresh)) {
+ channel->irq_moderation =
+ min(channel->irq_moderation +
+ FALCON_IRQ_MOD_RESOLUTION,
+ efx->irq_rx_moderation);
+ }
+
+ if (channel->irq_moderation != old_irq_moderation)
+ falcon_set_int_moderation(channel);
+
+ channel->irq_count = 0;
+ channel->irq_mod_score = 0;
+ }
+
/* There is no race here; although napi_disable() will
* only wait for napi_complete(), this isn't a problem
* since efx_channel_processed() will have no effect if
@@ -991,7 +1030,7 @@
efx_set_channels(efx);
/* Initialise the interrupt moderation settings */
- efx_init_irq_moderation(efx, tx_irq_mod_usec, rx_irq_mod_usec);
+ efx_init_irq_moderation(efx, tx_irq_mod_usec, rx_irq_mod_usec, true);
return 0;
}
@@ -1188,7 +1227,8 @@
**************************************************************************/
/* Set interrupt moderation parameters */
-void efx_init_irq_moderation(struct efx_nic *efx, int tx_usecs, int rx_usecs)
+void efx_init_irq_moderation(struct efx_nic *efx, int tx_usecs, int rx_usecs,
+ bool rx_adaptive)
{
struct efx_tx_queue *tx_queue;
struct efx_rx_queue *rx_queue;
@@ -1198,6 +1238,8 @@
efx_for_each_tx_queue(tx_queue, efx)
tx_queue->channel->irq_moderation = tx_usecs;
+ efx->irq_rx_adaptive = rx_adaptive;
+ efx->irq_rx_moderation = rx_usecs;
efx_for_each_rx_queue(rx_queue, efx)
rx_queue->channel->irq_moderation = rx_usecs;
}