From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: [PATCH v2 2/2] ahci: switch from 'threaded' to 'hardirq' interrupt handling Date: Sun, 01 Nov 2015 13:43:45 -0500 Message-ID: <20151101184345.23222.58353.stgit@dwillia2-desk3.amr.corp.intel.com> References: <20151101184335.23222.22225.stgit@dwillia2-desk3.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mga14.intel.com ([192.55.52.115]:62133 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752937AbbKASt2 (ORCPT ); Sun, 1 Nov 2015 13:49:28 -0500 In-Reply-To: <20151101184335.23222.22225.stgit@dwillia2-desk3.amr.corp.intel.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: tj@kernel.org Cc: linux-ide@vger.kernel.org For high frequency I/O the overhead of threaded interrupts impacts performance. Add an option to make it configurable, with the default being hardirq. 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 --- drivers/ata/libahci.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c index c6f098a0435c..f10a702abfb5 100644 --- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -1826,6 +1826,26 @@ static irqreturn_t ahci_multi_irqs_intr(int irq, void *dev_instance) return IRQ_WAKE_THREAD; } +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); + u32 status; + + VPRINTK("ENTER\n"); + + status = readl(port_mmio + PORT_IRQ_STAT); + writel(status, port_mmio + PORT_IRQ_STAT); + + spin_lock(ap->lock); + ahci_handle_port_interrupt(ap, port_mmio, status); + spin_unlock(ap->lock); + + VPRINTK("EXIT\n"); + + return IRQ_HANDLED; +} + static u32 ahci_handle_port_intr(struct ata_host *host, u32 irq_masked) { unsigned int i, handled = 0; @@ -2492,10 +2512,9 @@ 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);