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ahci: switch from 'threaded' to 'hardirq' interrupt handling

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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>
This commit is contained in:
Dan Williams 2015-11-11 16:27:38 -08:00 committed by Tejun Heo
parent d684a90d38
commit a6b7fb764e
1 changed files with 8 additions and 26 deletions
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34
drivers/ata/libahci.c
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@ -1796,29 +1796,10 @@ 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)
{
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 @@ static irqreturn_t ahci_multi_irqs_intr(int irq, void *dev_instance)
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);