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>
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@ -1796,29 +1796,10 @@ static void ahci_port_intr(struct ata_port *ap)
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ahci_handle_port_interrupt(ap, port_mmio, status);
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}
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static irqreturn_t ahci_port_thread_fn(int irq, void *dev_instance)
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{
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struct ata_port *ap = dev_instance;
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struct ahci_port_priv *pp = ap->private_data;
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void __iomem *port_mmio = ahci_port_base(ap);
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u32 status;
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status = atomic_xchg(&pp->intr_status, 0);
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if (!status)
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return IRQ_NONE;
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spin_lock_bh(ap->lock);
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ahci_handle_port_interrupt(ap, port_mmio, status);
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spin_unlock_bh(ap->lock);
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return IRQ_HANDLED;
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}
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static irqreturn_t ahci_multi_irqs_intr(int irq, void *dev_instance)
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static irqreturn_t ahci_multi_irqs_intr_hard(int irq, void *dev_instance)
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{
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struct ata_port *ap = dev_instance;
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void __iomem *port_mmio = ahci_port_base(ap);
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struct ahci_port_priv *pp = ap->private_data;
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u32 status;
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VPRINTK("ENTER\n");
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@ -1826,11 +1807,13 @@ static irqreturn_t ahci_multi_irqs_intr(int irq, void *dev_instance)
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status = readl(port_mmio + PORT_IRQ_STAT);
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writel(status, port_mmio + PORT_IRQ_STAT);
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atomic_or(status, &pp->intr_status);
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spin_lock(ap->lock);
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ahci_handle_port_interrupt(ap, port_mmio, status);
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spin_unlock(ap->lock);
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VPRINTK("EXIT\n");
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return IRQ_WAKE_THREAD;
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return IRQ_HANDLED;
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}
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static u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked)
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@ -2499,10 +2482,9 @@ static int ahci_host_activate_multi_irqs(struct ata_host *host,
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continue;
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}
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rc = devm_request_threaded_irq(host->dev, irq,
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ahci_multi_irqs_intr,
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ahci_port_thread_fn, 0,
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pp->irq_desc, host->ports[i]);
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rc = devm_request_irq(host->dev, irq, ahci_multi_irqs_intr_hard,
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0, pp->irq_desc, host->ports[i]);
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if (rc)
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return rc;
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ata_port_desc(host->ports[i], "irq %d", irq);
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