From: Thomas Gleixner <tglx@linutronix.de> To: Abel <wuyun.wu@huawei.com> Cc: Jiang Liu <jiang.liu@linux.intel.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Bjorn Helgaas <bhelgaas@google.com>, Randy Dunlap <rdunlap@infradead.org>, Yinghai Lu <yinghai@kernel.org>, Borislav Petkov <bp@alien8.de>, Grant Likely <grant.likely@linaro.org>, Marc Zyngier <marc.zyngier@arm.com>, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>, Andrew Morton <akpm@linux-foundation.org>, Tony Luck <tony.luck@intel.com>, Joerg Roedel <joro@8bytes.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, x86@kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [RFT v2 01/24] irqdomain: Introduce new interfaces to support hierarchy irqdomains Date: Tue, 30 Sep 2014 23:49:15 +0200 (CEST) [thread overview] Message-ID: <alpine.DEB.2.11.1409302337130.4455@nanos> (raw) In-Reply-To: <542A8C5E.3040901@huawei.com> On Tue, 30 Sep 2014, Abel wrote: > On 2014/9/29 23:53, Thomas Gleixner wrote: > What I suggest is something like: > > for (iter = domain; iter; iter = iter->parent) { > ret = iter->ops->alloc(iter, virq, nr_irqs, arg); > if (ret < 0) { > mutex_unlock(&irq_domain_mutex); > goto out_free_irq_data; > } > } > > in this way, the core infrastructure guarantees allocating down the > irqdomain hierarchy, and the implementers of domain_ops->alloc() > need not to call irq_domain_alloc_irqs_parent() any longer, just do > the things they have to. That makes sense. I misunderstood you then. > > So we cannot define upfront how deep an ack/mask/unmask/... has to be > > propagated down the chain. This needs a careful consideration in terms > > of functionality and we want to be able to do performance shortcuts as > > well. > > > > Yes, I got it. And one more thing I concerned is that when hierarchy > irqdomains is enabled, shouldn't the ack_parent() be called by default > by the irqchip->irq_ack() of each domain to ensure all the domains in > the delivery path ack this interrupt? In the pure theory of design, yes. But that will cause pointless overhead on particular systems. On a particular system the ack of the top level domain C, i.e. the one which is facing the device and is handled by the core irq flow handler, might be enough because B does not require an ack and A is implicitely acked by iret or some other magic instruction in the low level entry path. And because we know that C can only be on top of B and B is on top of A we want the flexibility to avoid going down the full chain for nothing in the interrupt hot path. So yes, in theory it should go down all levels, but in practice we dont want to enforce it :) Thanks, tglx
WARNING: multiple messages have this Message-ID (diff)
From: tglx@linutronix.de (Thomas Gleixner) To: linux-arm-kernel@lists.infradead.org Subject: [RFT v2 01/24] irqdomain: Introduce new interfaces to support hierarchy irqdomains Date: Tue, 30 Sep 2014 23:49:15 +0200 (CEST) [thread overview] Message-ID: <alpine.DEB.2.11.1409302337130.4455@nanos> (raw) In-Reply-To: <542A8C5E.3040901@huawei.com> On Tue, 30 Sep 2014, Abel wrote: > On 2014/9/29 23:53, Thomas Gleixner wrote: > What I suggest is something like: > > for (iter = domain; iter; iter = iter->parent) { > ret = iter->ops->alloc(iter, virq, nr_irqs, arg); > if (ret < 0) { > mutex_unlock(&irq_domain_mutex); > goto out_free_irq_data; > } > } > > in this way, the core infrastructure guarantees allocating down the > irqdomain hierarchy, and the implementers of domain_ops->alloc() > need not to call irq_domain_alloc_irqs_parent() any longer, just do > the things they have to. That makes sense. I misunderstood you then. > > So we cannot define upfront how deep an ack/mask/unmask/... has to be > > propagated down the chain. This needs a careful consideration in terms > > of functionality and we want to be able to do performance shortcuts as > > well. > > > > Yes, I got it. And one more thing I concerned is that when hierarchy > irqdomains is enabled, shouldn't the ack_parent() be called by default > by the irqchip->irq_ack() of each domain to ensure all the domains in > the delivery path ack this interrupt? In the pure theory of design, yes. But that will cause pointless overhead on particular systems. On a particular system the ack of the top level domain C, i.e. the one which is facing the device and is handled by the core irq flow handler, might be enough because B does not require an ack and A is implicitely acked by iret or some other magic instruction in the low level entry path. And because we know that C can only be on top of B and B is on top of A we want the flexibility to avoid going down the full chain for nothing in the interrupt hot path. So yes, in theory it should go down all levels, but in practice we dont want to enforce it :) Thanks, tglx
next prev parent reply other threads:[~2014-09-30 21:49 UTC|newest] Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-09-26 14:02 [RFT Part2 v2 00/24] Enable hierarchy irqdomian on x86 platforms Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 01/24] irqdomain: Introduce new interfaces to support hierarchy irqdomains Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-29 12:22 ` Abel 2014-09-29 12:22 ` Abel 2014-09-29 12:22 ` Abel 2014-09-29 15:53 ` Thomas Gleixner 2014-09-29 15:53 ` Thomas Gleixner 2014-09-30 10:56 ` Abel 2014-09-30 10:56 ` Abel 2014-09-30 10:56 ` Abel 2014-09-30 21:49 ` Thomas Gleixner [this message] 2014-09-30 21:49 ` Thomas Gleixner 2014-10-07 1:50 ` Jiang Liu 2014-10-07 1:50 ` Jiang Liu 2014-10-07 1:26 ` Jiang Liu 2014-10-07 1:26 ` Jiang Liu 2014-10-01 14:23 ` Joe.C 2014-10-01 14:23 ` Joe.C 2014-10-22 7:24 ` Jiang Liu 2014-10-22 7:24 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 02/24] genirq: Introduce helper functions to support stacked irq_chip Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 03/24] x86, irq: Save destination CPU ID in irq_cfg Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 04/24] x86, irq: Use hierarchy irqdomain to manage CPU interrupt vectors Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 05/24] x86, hpet: Use new irqdomain interfaces to allocate/free IRQ Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 06/24] x86, MSI: " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 07/24] x86, uv: " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 08/24] x86, htirq: " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 09/24] x86, dmar: " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 10/24] x86: irq_remapping: Introduce new interfaces to support hierarchy irqdomain Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 11/24] iommu/vt-d: Change prototypes to prepare for enabling " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 12/24] iommu/vt-d: Enhance Intel IR driver to suppport " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 13/24] iommu/amd: Enhance AMD " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 14/24] x86, hpet: Enhance HPET IRQ to support " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 15/24] x86, MSI: Use hierarchy irqdomain to manage MSI interrupts Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 16/24] x86, irq: Directly call native_compose_msi_msg() for DMAR IRQ Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 17/24] iommu/vt-d: Clean up unused MSI related code Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 18/24] iommu/amd: " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 19/24] x86: irq_remapping: " Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 20/24] x86, irq: Clean up unused MSI related code and interfaces Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 21/24] iommu/vt-d: Refine the interfaces to create IRQ for DMAR unit Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 22/24] x86, irq: Use hierarchy irqdomain to manage DMAR interrupts Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 23/24] x86, htirq: Use hierarchy irqdomain to manage Hypertransport interrupts Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:02 ` [RFT v2 24/24] x86, uv: Use hierarchy irqdomain to manage UV interrupts Jiang Liu 2014-09-26 14:02 ` Jiang Liu 2014-09-26 14:29 ` [RFT Part2 v2 00/24] Enable hierarchy irqdomian on x86 platforms Borislav Petkov 2014-09-26 14:29 ` Borislav Petkov 2014-09-26 16:30 ` Aravind Gopalakrishnan 2014-09-26 16:30 ` Aravind Gopalakrishnan 2014-09-26 16:30 ` Aravind Gopalakrishnan 2014-09-28 11:05 ` Borislav Petkov 2014-09-28 11:05 ` Borislav Petkov 2014-09-28 11:15 ` Jiang Liu 2014-09-28 11:15 ` Jiang Liu
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