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Date: Fri, 28 Aug 2009 01:20:24 +0200
From: Francois Romieu <romieu@...zoreil.com>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: David Dillow <dave@...dillows.org>,
Michael Riepe <michael.riepe@...glemail.com>,
Michael Buesch <mb@...sch.de>,
Rui Santos <rsantos@...popie.com>,
Michael B??ker <m.bueker@...lin.de>,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] r8169: Reduce looping in the interrupt handler.
Eric W. Biederman <ebiederm@...ssion.com> :
[...]
> Sounds good.
Gah, I was not able to test it with a decent packet load. Patch below against
the current tree:
diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c
index b82780d..6596ef6 100644
--- a/drivers/net/r8169.c
+++ b/drivers/net/r8169.c
@@ -3549,21 +3549,39 @@ static int rtl8169_rx_interrupt(struct net_device *dev,
return count;
}
+static void rtl_napi_cond_schedule(struct rtl8169_private *tp, u16 status)
+{
+ if (status & tp->napi_event) {
+ void __iomem *ioaddr = tp->mmio_addr;
+
+ RTL_W16(IntrMask, tp->intr_event & ~tp->napi_event);
+ mmiowb();
+ napi_schedule(&tp->napi);
+ }
+}
+
static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance)
{
struct net_device *dev = dev_instance;
struct rtl8169_private *tp = netdev_priv(dev);
void __iomem *ioaddr = tp->mmio_addr;
int handled = 0;
- int status;
+ u16 status;
/* loop handling interrupts until we have no new ones or
* we hit a invalid/hotplug case.
*/
status = RTL_R16(IntrStatus);
while (status && status != 0xffff) {
+ u16 acked;
+
handled = 1;
+ acked = (status & RxFIFOOver) ? (status | RxOverflow) : status;
+ acked &= ~tp->napi_event;
+
+ RTL_W16(IntrStatus, acked);
+
/* Handle all of the error cases first. These will reset
* the chip, so just exit the loop.
*/
@@ -3574,7 +3592,7 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance)
/* Work around for rx fifo overflow */
if (unlikely(status & RxFIFOOver) &&
- (tp->mac_version == RTL_GIGA_MAC_VER_11)) {
+ (tp->mac_version == RTL_GIGA_MAC_VER_11)) {
netif_stop_queue(dev);
rtl8169_tx_timeout(dev);
break;
@@ -3588,31 +3606,9 @@ static irqreturn_t rtl8169_interrupt(int irq, void *dev_instance)
if (status & LinkChg)
rtl8169_check_link_status(dev, tp, ioaddr);
- /* We need to see the lastest version of tp->intr_mask to
- * avoid ignoring an MSI interrupt and having to wait for
- * another event which may never come.
- */
- smp_rmb();
- if (status & tp->intr_mask & tp->napi_event) {
- RTL_W16(IntrMask, tp->intr_event & ~tp->napi_event);
- tp->intr_mask = ~tp->napi_event;
-
- if (likely(napi_schedule_prep(&tp->napi)))
- __napi_schedule(&tp->napi);
- else if (netif_msg_intr(tp)) {
- printk(KERN_INFO "%s: interrupt %04x in poll\n",
- dev->name, status);
- }
- }
+ rtl_napi_cond_schedule(tp, status);
- /* We only get a new MSI interrupt when all active irq
- * sources on the chip have been acknowledged. So, ack
- * everything we've seen and check if new sources have become
- * active to avoid blocking all interrupts from the chip.
- */
- RTL_W16(IntrStatus,
- (status & RxFIFOOver) ? (status | RxOverflow) : status);
- status = RTL_R16(IntrStatus);
+ break;
}
return IRQ_RETVAL(handled);
@@ -3625,22 +3621,19 @@ static int rtl8169_poll(struct napi_struct *napi, int budget)
void __iomem *ioaddr = tp->mmio_addr;
int work_done;
+
+ RTL_W16(IntrStatus, tp->napi_event);
+
work_done = rtl8169_rx_interrupt(dev, tp, ioaddr, (u32) budget);
rtl8169_tx_interrupt(dev, tp, ioaddr);
if (work_done < budget) {
napi_complete(napi);
- /* We need for force the visibility of tp->intr_mask
- * for other CPUs, as we can loose an MSI interrupt
- * and potentially wait for a retransmit timeout if we don't.
- * The posted write to IntrMask is safe, as it will
- * eventually make it to the chip and we won't loose anything
- * until it does.
- */
- tp->intr_mask = 0xffff;
- smp_wmb();
RTL_W16(IntrMask, tp->intr_event);
+ mmiowb();
+
+ rtl_napi_cond_schedule(tp, RTL_R16(IntrStatus));
}
return work_done;
--
Ueimor
--
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