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pasemi_mac: Improve RX interrupt mitigation 

pasemi_mac: Improve RX interrupt mitigation

Currently the receive side interrupts will go off on the reception of
a packet, NAPI will poll the ring and keep polling as long as there's
a decent amount of packets to receive.

This is less than optimal, especially for LRO where it's better if we
have a more substantial amount of packets to process at once, to get
the real LRO benefits.

So, set the count threshold to a higher value and use the timeout feature
that will give us an interrupt even if not enough packets have come in
to set off the count threshold.

FIXME: It'd be real nice to have ethtool support for users to tune this
at runtime.

Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
This commit is contained in:
Olof Johansson 2007-11-28 20:57:09 -06:00 committed by David S. Miller
parent 61cec3bddc
commit 906674abab
1 changed files with 10 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/net/pasemi_mac.c
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@ -504,15 +504,19 @@ static void pasemi_mac_replenish_rx_ring(const struct net_device *dev,
static void pasemi_mac_restart_rx_intr(const struct pasemi_mac *mac)
{
struct pasemi_mac_rxring *rx = rx_ring(mac);
unsigned int reg, pcnt;
/* Re-enable packet count interrupts: finally
* ack the packet count interrupt we got in rx_intr.
*/
pcnt = *rx_ring(mac)->chan.status & PAS_STATUS_PCNT_M;
pcnt = *rx->chan.status & PAS_STATUS_PCNT_M;
reg = PAS_IOB_DMA_RXCH_RESET_PCNT(pcnt) | PAS_IOB_DMA_RXCH_RESET_PINTC;
if (*rx->chan.status & PAS_STATUS_TIMER)
reg |= PAS_IOB_DMA_RXCH_RESET_TINTC;
write_iob_reg(PAS_IOB_DMA_RXCH_RESET(mac->rx->chan.chno), reg);
}
@ -795,8 +799,6 @@ static irqreturn_t pasemi_mac_rx_intr(int irq, void *data)
reg |= PAS_IOB_DMA_RXCH_RESET_SINTC;
if (*chan->status & PAS_STATUS_ERROR)
reg |= PAS_IOB_DMA_RXCH_RESET_DINTC;
if (*chan->status & PAS_STATUS_TIMER)
reg |= PAS_IOB_DMA_RXCH_RESET_TINTC;
netif_rx_schedule(dev, &mac->napi);
@ -972,10 +974,6 @@ static int pasemi_mac_open(struct net_device *dev)
write_mac_reg(mac, PAS_MAC_CFG_TXP, flags);
/* 0xffffff is max value, about 16ms */
write_iob_reg(PAS_IOB_DMA_COM_TIMEOUTCFG,
PAS_IOB_DMA_COM_TIMEOUTCFG_TCNT(0xffffff));
ret = pasemi_mac_setup_rx_resources(dev);
if (ret)
goto out_rx_resources;
@ -985,8 +983,12 @@ static int pasemi_mac_open(struct net_device *dev)
if (!mac->tx)
goto out_tx_ring;
/* 0x3ff with 33MHz clock is about 31us */
write_iob_reg(PAS_IOB_DMA_COM_TIMEOUTCFG,
PAS_IOB_DMA_COM_TIMEOUTCFG_TCNT(0x3ff));
write_iob_reg(PAS_IOB_DMA_RXCH_CFG(mac->rx->chan.chno),
PAS_IOB_DMA_RXCH_CFG_CNTTH(0));
PAS_IOB_DMA_RXCH_CFG_CNTTH(128));
write_iob_reg(PAS_IOB_DMA_TXCH_CFG(mac->tx->chan.chno),
PAS_IOB_DMA_TXCH_CFG_CNTTH(32));