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Date: Tue, 29 Apr 2008 17:26:05 +0800
From: "Li Yang" <LeoLi@...escale.com>
To: "Joakim Tjernlund" <Joakim.Tjernlund@...nsmode.se>,
"Netdev" <netdev@...r.kernel.org>
Subject: RE: [PATCH] ucc_geth: Ack IRQ events as late as possible.
> -----Original Message-----
> From: Joakim Tjernlund [mailto:Joakim.Tjernlund@...nsmode.se]
> Sent: Friday, April 25, 2008 11:43 PM
> To: Li Yang; Netdev
> Cc: Joakim Tjernlund
> Subject: [PATCH] ucc_geth: Ack IRQ events as late as possible.
>
> Late acking of IRQ events will reduce number of interrupts
> that needs to be served.
>
> Makes the system somewhat responsive during a ping -f -l 10
>
> Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@...nsmode.se>
> ---
> drivers/net/ucc_geth.c | 36 ++++++++++++++++++++++--------------
> drivers/net/ucc_geth.h | 4 ++--
> 2 files changed, 24 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/net/ucc_geth.c b/drivers/net/ucc_geth.c
> index 28431aa..c6bf4d3 100644
> --- a/drivers/net/ucc_geth.c
> +++ b/drivers/net/ucc_geth.c
> @@ -3449,6 +3449,7 @@ static int ucc_geth_rx(struct
> ucc_geth_private *ugeth, u8 rxQ, int rx_work_limit
> u32 bd_status;
> u8 *bdBuffer;
> struct net_device *dev;
> + struct ucc_fast_private *uccf = ugeth->uccf;
>
> ugeth_vdbg("%s: IN", __FUNCTION__);
>
> @@ -3457,10 +3458,21 @@ static int ucc_geth_rx(struct
> ucc_geth_private *ugeth, u8 rxQ, int rx_work_limit
> /* collect received buffers */
> bd = ugeth->rxBd[rxQ];
>
> - bd_status = in_be32((u32 *)bd);
> -
> /* while there are received buffers and BD is full (~R_E) */
> - while (!((bd_status & (R_E)) || (--rx_work_limit < 0))) {
> + while (1) {
> + if (in_be32(uccf->p_ucce) & UCCE_BSY) {
> + dev->stats.rx_missed_errors++;
> + dev->stats.rx_errors++;
> + }
> + out_be32(uccf->p_ucce, UCCE_RX_EVENTS);
> +
> + if (--rx_work_limit < 0)
> + break;
> +
> + bd_status = in_be32((u32 *)bd);
> + if (bd_status & R_E)
> + break; /* No more RX buffers */
> +
> bdBuffer = (u8 *) in_be32(&((struct qe_bd *)bd)->buf);
> length = (u16) ((bd_status & BD_LENGTH_MASK) - 4);
> skb = ugeth->rx_skbuff[rxQ][ugeth->skb_currx[rxQ]];
> @@ -3530,6 +3542,7 @@ static int ucc_geth_tx(struct
> net_device *dev, u8 txQ) {
> /* Start from the next BD that should be filled */
> struct ucc_geth_private *ugeth = netdev_priv(dev);
> + struct ucc_fast_private *uccf = ugeth->uccf;
> u8 *bd; /* BD pointer */
> u32 bd_status;
>
> @@ -3541,6 +3554,7 @@ static int ucc_geth_tx(struct
> net_device *dev, u8 txQ)
> /* BD contains already transmitted buffer. */
> /* Handle the transmitted buffer and release */
> /* the BD to be used with the current frame */
> + out_be32(uccf->p_ucce, UCCE_TX_EVENTS);
>
> if ((bd == ugeth->txBd[txQ]) &&
> (netif_queue_stopped(dev) == 0))
> break;
> @@ -3619,10 +3633,8 @@ static irqreturn_t
> ucc_geth_irq_handler(int irq, void *info)
> ug_info = ugeth->ug_info;
>
> /* read and clear events */
> - ucce = (u32) in_be32(uccf->p_ucce);
> uccm = (u32) in_be32(uccf->p_uccm);
> - ucce &= uccm;
> - out_be32(uccf->p_ucce, ucce);
> + ucce = (u32) in_be32(uccf->p_ucce) & uccm;
>
> /* check for receive events that require processing */
> if (ucce & UCCE_RX_EVENTS) {
> @@ -3643,6 +3655,7 @@ static irqreturn_t
> ucc_geth_irq_handler(int irq, void *info) #endif /*
> CONFIG_UGETH_NAPI */
> }
>
> + ucce = (u32) in_be32(uccf->p_ucce) & uccm;
> /* Tx event processing */
> if (ucce & UCCE_TX_EVENTS) {
> spin_lock(&ugeth->lock);
> @@ -3655,15 +3668,10 @@ static irqreturn_t
> ucc_geth_irq_handler(int irq, void *info)
> }
> spin_unlock(&ugeth->lock);
> }
> -
> - /* Errors and other events */
> + ucce = (u32) in_be32(uccf->p_ucce) & uccm;
> + /* Other events */
> if (ucce & UCCE_OTHER) {
> - if (ucce & UCCE_BSY) {
> - dev->stats.rx_errors++;
> - }
> - if (ucce & UCCE_TXE) {
> - dev->stats.tx_errors++;
> - }
> + out_be32(uccf->p_ucce, UCCE_OTHER);
> }
>
> return IRQ_HANDLED;
> diff --git a/drivers/net/ucc_geth.h b/drivers/net/ucc_geth.h
> index cc24e87..7451f17 100644
> --- a/drivers/net/ucc_geth.h
> +++ b/drivers/net/ucc_geth.h
> @@ -207,8 +207,8 @@ struct ucc_geth {
> UCCE_RXB3 | UCCE_RXB2 | UCCE_RXB1 | UCCE_RXB0)
> #define UCCE_RXF (UCCE_RXF7 | UCCE_RXF6 | UCCE_RXF5
> | UCCE_RXF4 |\
> UCCE_RXF3 | UCCE_RXF2 | UCCE_RXF1 | UCCE_RXF0)
> -#define UCCE_OTHER (UCCE_SCAR | UCCE_GRA | UCCE_CBPR
> | UCCE_BSY |\
> - UCCE_RXC | UCCE_TXC | UCCE_TXE)
> +#define UCCE_OTHER (UCCE_SCAR | UCCE_GRA | UCCE_CBPR |\
> + UCCE_RXC | UCCE_TXC)
This will remove UCCE_BSY and UCCE_TXE from the uccm_mask, hence
disabled them from generating interrupts.
How is the improvement after your change to put off interrupt ack?
Isn't it caused by disabling the busy interrupts?
- Leo
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