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Commit a6b7fb76 authored by Dan Williams's avatar Dan Williams Committed by Tejun Heo
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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: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent d684a90d

drivers/ata/libahci.c

+8 −26
Original line number Diff line number Diff line
@@ -1796,41 +1796,24 @@ static void ahci_port_intr(struct ata_port *ap) 
	ahci_handle_port_interrupt(ap, port_mmio, status);

}



static irqreturn_t ahci_port_thread_fn(int irq, void *dev_instance)

static irqreturn_t ahci_multi_irqs_intr_hard(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)

{

	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");



	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 @@ static int ahci_host_activate_multi_irqs(struct ata_host *host, 
			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);