ahci: switch from 'threaded' to 'hardirq' interrupt handling
For high frequency I/O the overhead of threaded interrupts impacts
performance. A quick out-of-the-box test (i.e. no affinity tuning)
shows ~10% random read performance at ~20% less cpu. The cpu wins
appear to be from reduced lock contention.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 0a5645f..1b6c7cc 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -1796,29 +1796,10 @@
ahci_handle_port_interrupt(ap, port_mmio, status);
}
-static irqreturn_t ahci_port_thread_fn(int irq, void *dev_instance)
-{
- struct ata_port *ap = dev_instance;
- struct ahci_port_priv *pp = ap->private_data;
- void __iomem *port_mmio = ahci_port_base(ap);
- u32 status;
-
- status = atomic_xchg(&pp->intr_status, 0);
- if (!status)
- return IRQ_NONE;
-
- spin_lock_bh(ap->lock);
- ahci_handle_port_interrupt(ap, port_mmio, status);
- spin_unlock_bh(ap->lock);
-
- return IRQ_HANDLED;
-}
-
-static irqreturn_t ahci_multi_irqs_intr(int irq, void *dev_instance)
+static irqreturn_t ahci_multi_irqs_intr_hard(int irq, void *dev_instance)
{
struct ata_port *ap = dev_instance;
void __iomem *port_mmio = ahci_port_base(ap);
- struct ahci_port_priv *pp = ap->private_data;
u32 status;
VPRINTK("ENTER\n");
@@ -1826,11 +1807,13 @@
status = readl(port_mmio + PORT_IRQ_STAT);
writel(status, port_mmio + PORT_IRQ_STAT);
- atomic_or(status, &pp->intr_status);
+ spin_lock(ap->lock);
+ ahci_handle_port_interrupt(ap, port_mmio, status);
+ spin_unlock(ap->lock);
VPRINTK("EXIT\n");
- return IRQ_WAKE_THREAD;
+ return IRQ_HANDLED;
}
static u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked)
@@ -2499,10 +2482,9 @@
continue;
}
- rc = devm_request_threaded_irq(host->dev, irq,
- ahci_multi_irqs_intr,
- ahci_port_thread_fn, 0,
- pp->irq_desc, host->ports[i]);
+ rc = devm_request_irq(host->dev, irq, ahci_multi_irqs_intr_hard,
+ 0, pp->irq_desc, host->ports[i]);
+
if (rc)
return rc;
ata_port_desc(host->ports[i], "irq %d", irq);