From patchwork Thu Nov 12 00:27:38 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 543155 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id D5AD21402BF for ; Thu, 12 Nov 2015 11:28:08 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752323AbbKLA2I (ORCPT ); Wed, 11 Nov 2015 19:28:08 -0500 Received: from mga01.intel.com ([192.55.52.88]:27723 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751911AbbKLA2H (ORCPT ); Wed, 11 Nov 2015 19:28:07 -0500 Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga101.fm.intel.com with ESMTP; 11 Nov 2015 16:28:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.20,279,1444719600"; d="scan'208";a="683353628" Received: from dwillia2-desk3.jf.intel.com ([10.54.39.39]) by orsmga003.jf.intel.com with ESMTP; 11 Nov 2015 16:28:07 -0800 Subject: [PATCH v3 2/2] ahci: switch from 'threaded' to 'hardirq' interrupt handling From: Dan Williams To: tj@kernel.org Cc: linux-ide@vger.kernel.org Date: Wed, 11 Nov 2015 16:27:38 -0800 Message-ID: <20151112002738.37012.56239.stgit@dwillia2-desk3.jf.intel.com> In-Reply-To: <20151112002727.37012.65672.stgit@dwillia2-desk3.jf.intel.com> References: <20151112002727.37012.65672.stgit@dwillia2-desk3.jf.intel.com> User-Agent: StGit/0.17.1-9-g687f MIME-Version: 1.0 Sender: linux-ide-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ide@vger.kernel.org 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 --- drivers/ata/libahci.c | 34 ++++++++-------------------------- 1 file changed, 8 insertions(+), 26 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c index 0a5645fb02f8..1b6c7cc415bf 100644 --- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -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);