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Date: Fri, 31 Aug 2007 09:05:41 -0400
From: Jeff Garzik <jeff@...zik.org>
To: ram.vepa@...erion.com
CC: netdev@...r.kernel.org, support@...erion.com
Subject: Re: [PATCH 2.6.24 5/5]S2io: Optimize isr fast path
Ramkrishna Vepa wrote:
> - Optimized interrupt routine fast path.
>
> Signed-off-by: Sivakumar Subramani <sivakumar.subramani@...erion.com>
> Signed-off-by: Santosh Rastapur <santosh.rastapur@...erion.com>
> Signed-off-by: Ramkrishna Vepa <ram.vepa@...erion.com>
patch description is completely inadequate. how was it optimized? what
are the gains / why is this patch worth having?
> diff -Nurp patch4/drivers/net/s2io.c patch5/drivers/net/s2io.c
> --- patch4/drivers/net/s2io.c 2007-08-15 08:42:14.000000000 -0700
> +++ patch5/drivers/net/s2io.c 2007-08-15 08:42:51.000000000 -0700
> @@ -84,7 +84,7 @@
> #include "s2io.h"
> #include "s2io-regs.h"
>
> -#define DRV_VERSION "2.0.26.1"
> +#define DRV_VERSION "2.0.26.2"
>
> /* S2io Driver name & version. */
> static char s2io_driver_name[] = "Neterion";
> @@ -4917,71 +4917,76 @@ static irqreturn_t s2io_isr(int irq, voi
> * 1. Rx of packet.
> * 2. Tx complete.
> * 3. Link down.
> - * 4. Error in any functional blocks of the NIC.
> */
> reason = readq(&bar0->general_int_status);
>
> - if (!reason) {
> - /* The interrupt was not raised by us. */
> + if (unlikely(reason == S2IO_MINUS_ONE) ) {
> + /* Nothing much can be done. Get out */
> atomic_dec(&sp->isr_cnt);
> - return IRQ_NONE;
> - }
> - else if (unlikely(reason == S2IO_MINUS_ONE) ) {
> - /* Disable device and get out */
> - atomic_dec(&sp->isr_cnt);
> - return IRQ_NONE;
> + return IRQ_HANDLED;
> }
>
> - if (napi) {
> - if (reason & GEN_INTR_RXTRAFFIC) {
> - if ( likely ( netif_rx_schedule_prep(dev)) ) {
> - __netif_rx_schedule(dev);
> - writeq(S2IO_MINUS_ONE, &bar0->rx_traffic_mask);
> + if (reason & (GEN_INTR_RXTRAFFIC |
> + GEN_INTR_TXTRAFFIC | GEN_INTR_TXPIC))
> + {
> + writeq(S2IO_MINUS_ONE, &bar0->general_int_mask);
> +
> + if (config->napi) {
> + if (reason & GEN_INTR_RXTRAFFIC) {
> + if ( likely (netif_rx_schedule_prep(dev)) ) {
> + __netif_rx_schedule(dev);
> + writeq(S2IO_MINUS_ONE,
> + &bar0->rx_traffic_mask);
> + } else
> + writeq(S2IO_MINUS_ONE,
> + &bar0->rx_traffic_int);
> }
> - else
> + } else {
> + /*
> + * rx_traffic_int reg is an R1 register, writing all 1's
> + * will ensure that the actual interrupt causing bit
> + * get's cleared and hence a read can be avoided.
> + */
> + if (reason & GEN_INTR_RXTRAFFIC)
> writeq(S2IO_MINUS_ONE, &bar0->rx_traffic_int);
> +
> + for (i = 0; i < config->rx_ring_num; i++)
> + rx_intr_handler(&mac_control->rings[i]);
> }
> - } else {
> +
> /*
> - * Rx handler is called by default, without checking for the
> - * cause of interrupt.
> - * rx_traffic_int reg is an R1 register, writing all 1's
> + * tx_traffic_int reg is an R1 register, writing all 1's
> * will ensure that the actual interrupt causing bit get's
> * cleared and hence a read can be avoided.
> */
> - if (reason & GEN_INTR_RXTRAFFIC)
> - writeq(S2IO_MINUS_ONE, &bar0->rx_traffic_int);
> + if (reason & GEN_INTR_TXTRAFFIC)
> + writeq(S2IO_MINUS_ONE, &bar0->tx_traffic_int);
>
> - for (i = 0; i < config->rx_ring_num; i++) {
> - rx_intr_handler(&mac_control->rings[i]);
> - }
> - }
> + for (i = 0; i < config->tx_fifo_num; i++)
> + tx_intr_handler(&mac_control->fifos[i]);
>
> - /*
> - * tx_traffic_int reg is an R1 register, writing all 1's
> - * will ensure that the actual interrupt causing bit get's
> - * cleared and hence a read can be avoided.
> - */
> - if (reason & GEN_INTR_TXTRAFFIC)
> - writeq(S2IO_MINUS_ONE, &bar0->tx_traffic_int);
> + if (reason & GEN_INTR_TXPIC)
> + s2io_txpic_intr_handle(sp);
>
> - for (i = 0; i < config->tx_fifo_num; i++)
> - tx_intr_handler(&mac_control->fifos[i]);
> + /*
> + * Reallocate the buffers from the interrupt handler itself.
> + */
> + if (!config->napi) {
> + for (i = 0; i < config->rx_ring_num; i++)
> + s2io_chk_rx_buffers(sp, i);
> + }
> + writeq(sp->general_int_mask, &bar0->general_int_mask);
> + readl(&bar0->general_int_status);
>
> - if (reason & GEN_INTR_TXPIC)
> - s2io_txpic_intr_handle(sp);
> - /*
> - * If the Rx buffer count is below the panic threshold then
> - * reallocate the buffers from the interrupt handler itself,
> - * else schedule a tasklet to reallocate the buffers.
> - */
> - if (!napi) {
> - for (i = 0; i < config->rx_ring_num; i++)
> - s2io_chk_rx_buffers(sp, i);
> - }
> + atomic_dec(&sp->isr_cnt);
> + return IRQ_HANDLED;
>
> - writeq(0, &bar0->general_int_mask);
> - readl(&bar0->general_int_status);
> + }
> + else if (!reason) {
> + /* The interrupt was not raised by us */
> + atomic_dec(&sp->isr_cnt);
> + return IRQ_NONE;
> + }
>
> atomic_dec(&sp->isr_cnt);
> return IRQ_HANDLED;
> @@ -7109,6 +7114,14 @@ static void s2io_rem_isr(struct s2io_nic
> struct net_device *dev = sp->dev;
> struct swStat *stats = &sp->mac_control.stats_info->sw_stat;
>
> + /* Waiting till all Interrupt handlers are complete */
> + do {
> + if (!atomic_read(&sp->isr_cnt))
> + break;
> + msleep(10);
> + cnt++;
> + } while(cnt < 5);
> +
> if (sp->config.intr_type == MSI_X) {
> int i;
> u16 msi_control;
> @@ -7138,14 +7151,6 @@ static void s2io_rem_isr(struct s2io_nic
> } else {
> free_irq(sp->pdev->irq, dev);
> }
> - /* Waiting till all Interrupt handlers are complete */
> - cnt = 0;
> - do {
> - msleep(10);
> - if (!atomic_read(&sp->isr_cnt))
> - break;
> - cnt++;
> - } while(cnt < 5);
> }
this is bogus code -- you should use synchronize_irq() and other
standard kernel functions, rather than duplicating all that state in the
driver-private structs
-
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