From 9cfef55bb57e7620c63087be18a76351628f8d0f Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sat, 16 Feb 2019 18:13:08 +0100 Subject: genirq/affinity: Store interrupt sets size in struct irq_affinity The interrupt affinity spreading mechanism supports to spread out affinities for one or more interrupt sets. A interrupt set contains one or more interrupts. Each set is mapped to a specific functionality of a device, e.g. general I/O queues and read I/O queus of multiqueue block devices. The number of interrupts per set is defined by the driver. It depends on the total number of available interrupts for the device, which is determined by the PCI capabilites and the availability of underlying CPU resources, and the number of queues which the device provides and the driver wants to instantiate. The driver passes initial configuration for the interrupt allocation via a pointer to struct irq_affinity. Right now the allocation mechanism is complex as it requires to have a loop in the driver to determine the maximum number of interrupts which are provided by the PCI capabilities and the underlying CPU resources. This loop would have to be replicated in every driver which wants to utilize this mechanism. That's unwanted code duplication and error prone. In order to move this into generic facilities it is required to have a mechanism, which allows the recalculation of the interrupt sets and their size, in the core code. As the core code does not have any knowledge about the underlying device, a driver specific callback will be added to struct affinity_desc, which will be invoked by the core code. The callback will get the number of available interupts as an argument, so the driver can calculate the corresponding number and size of interrupt sets. To support this, two modifications for the handling of struct irq_affinity are required: 1) The (optional) interrupt sets size information is contained in a separate array of integers and struct irq_affinity contains a pointer to it. This is cumbersome and as the maximum number of interrupt sets is small, there is no reason to have separate storage. Moving the size array into struct affinity_desc avoids indirections and makes the code simpler. 2) At the moment the struct irq_affinity pointer which is handed in from the driver and passed through to several core functions is marked 'const'. With the upcoming callback to recalculate the number and size of interrupt sets, it's necessary to remove the 'const' qualifier. Otherwise the callback would not be able to update the data. Implement #1 and store the interrupt sets size in 'struct irq_affinity'. No functional change. [ tglx: Fixed the memcpy() size so it won't copy beyond the size of the source. Fixed the kernel doc comments for struct irq_affinity and de-'This patch'-ed the changelog ] Signed-off-by: Ming Lei Signed-off-by: Thomas Gleixner Acked-by: Marc Zyngier Cc: Christoph Hellwig Cc: Bjorn Helgaas Cc: Jens Axboe Cc: linux-block@vger.kernel.org Cc: Sagi Grimberg Cc: linux-nvme@lists.infradead.org Cc: linux-pci@vger.kernel.org Cc: Keith Busch Cc: Sumit Saxena Cc: Kashyap Desai Cc: Shivasharan Srikanteshwara Link: https://lkml.kernel.org/r/20190216172228.423723127@linutronix.de --- drivers/nvme/host/pci.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'drivers/nvme') diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 9bc585415d9b..21ffd671b6ed 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -2081,12 +2081,11 @@ static void nvme_calc_io_queues(struct nvme_dev *dev, unsigned int irq_queues) static int nvme_setup_irqs(struct nvme_dev *dev, unsigned int nr_io_queues) { struct pci_dev *pdev = to_pci_dev(dev->dev); - int irq_sets[2]; struct irq_affinity affd = { - .pre_vectors = 1, - .nr_sets = ARRAY_SIZE(irq_sets), - .sets = irq_sets, + .pre_vectors = 1, + .nr_sets = 2, }; + unsigned int *irq_sets = affd.set_size; int result = 0; unsigned int irq_queues, this_p_queues; -- cgit From 612b72862b4dd7f3f5e42651522daac6733b8ea6 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sat, 16 Feb 2019 18:13:10 +0100 Subject: nvme-pci: Simplify interrupt allocation The NVME PCI driver contains a tedious mechanism for interrupt allocation, which is necessary to adjust the number and size of interrupt sets to the maximum available number of interrupts which depends on the underlying PCI capabilities and the available CPU resources. It works around the former short comings of the PCI and core interrupt allocation mechanims in combination with interrupt sets. The PCI interrupt allocation function allows to provide a maximum and a minimum number of interrupts to be allocated and tries to allocate as many as possible. This worked without driver interaction as long as there was only a single set of interrupts to handle. With the addition of support for multiple interrupt sets in the generic affinity spreading logic, which is invoked from the PCI interrupt allocation, the adaptive loop in the PCI interrupt allocation did not work for multiple interrupt sets. The reason is that depending on the total number of interrupts which the PCI allocation adaptive loop tries to allocate in each step, the number and the size of the interrupt sets need to be adapted as well. Due to the way the interrupt sets support was implemented there was no way for the PCI interrupt allocation code or the core affinity spreading mechanism to invoke a driver specific function for adapting the interrupt sets configuration. As a consequence the driver had to implement another adaptive loop around the PCI interrupt allocation function and calling that with maximum and minimum interrupts set to the same value. This ensured that the allocation either succeeded or immediately failed without any attempt to adjust the number of interrupts in the PCI code. The core code now allows drivers to provide a callback to recalculate the number and the size of interrupt sets during PCI interrupt allocation, which in turn allows the PCI interrupt allocation function to be called in the same way as with a single set of interrupts. The PCI code handles the adaptive loop and the interrupt affinity spreading mechanism invokes the driver callback to adapt the interrupt set configuration to the current loop value. This replaces the adaptive loop in the driver completely. Implement the NVME specific callback which adjusts the interrupt sets configuration and remove the adaptive allocation loop. [ tglx: Simplify the callback further and restore the dropped adjustment of number of sets ] Signed-off-by: Ming Lei Signed-off-by: Thomas Gleixner Acked-by: Marc Zyngier Cc: Christoph Hellwig Cc: Bjorn Helgaas Cc: Jens Axboe Cc: linux-block@vger.kernel.org Cc: Sagi Grimberg Cc: linux-nvme@lists.infradead.org Cc: linux-pci@vger.kernel.org Cc: Keith Busch Cc: Sumit Saxena Cc: Kashyap Desai Cc: Shivasharan Srikanteshwara Link: https://lkml.kernel.org/r/20190216172228.602546658@linutronix.de --- drivers/nvme/host/pci.c | 114 ++++++++++++++++-------------------------------- 1 file changed, 38 insertions(+), 76 deletions(-) (limited to 'drivers/nvme') diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 21ffd671b6ed..a0fdd5fb4e7a 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -2041,41 +2041,42 @@ static int nvme_setup_host_mem(struct nvme_dev *dev) return ret; } -/* irq_queues covers admin queue */ -static void nvme_calc_io_queues(struct nvme_dev *dev, unsigned int irq_queues) +/* + * nirqs is the number of interrupts available for write and read + * queues. The core already reserved an interrupt for the admin queue. + */ +static void nvme_calc_irq_sets(struct irq_affinity *affd, unsigned int nrirqs) { - unsigned int this_w_queues = write_queues; - - WARN_ON(!irq_queues); - - /* - * Setup read/write queue split, assign admin queue one independent - * irq vector if irq_queues is > 1. - */ - if (irq_queues <= 2) { - dev->io_queues[HCTX_TYPE_DEFAULT] = 1; - dev->io_queues[HCTX_TYPE_READ] = 0; - return; - } - - /* - * If 'write_queues' is set, ensure it leaves room for at least - * one read queue and one admin queue - */ - if (this_w_queues >= irq_queues) - this_w_queues = irq_queues - 2; + struct nvme_dev *dev = affd->priv; + unsigned int nr_read_queues; /* - * If 'write_queues' is set to zero, reads and writes will share - * a queue set. + * If there is no interupt available for queues, ensure that + * the default queue is set to 1. The affinity set size is + * also set to one, but the irq core ignores it for this case. + * + * If only one interrupt is available or 'write_queue' == 0, combine + * write and read queues. + * + * If 'write_queues' > 0, ensure it leaves room for at least one read + * queue. */ - if (!this_w_queues) { - dev->io_queues[HCTX_TYPE_DEFAULT] = irq_queues - 1; - dev->io_queues[HCTX_TYPE_READ] = 0; + if (!nrirqs) { + nrirqs = 1; + nr_read_queues = 0; + } else if (nrirqs == 1 || !write_queues) { + nr_read_queues = 0; + } else if (write_queues >= nrirqs) { + nr_read_queues = 1; } else { - dev->io_queues[HCTX_TYPE_DEFAULT] = this_w_queues; - dev->io_queues[HCTX_TYPE_READ] = irq_queues - this_w_queues - 1; + nr_read_queues = nrirqs - write_queues; } + + dev->io_queues[HCTX_TYPE_DEFAULT] = nrirqs - nr_read_queues; + affd->set_size[HCTX_TYPE_DEFAULT] = nrirqs - nr_read_queues; + dev->io_queues[HCTX_TYPE_READ] = nr_read_queues; + affd->set_size[HCTX_TYPE_READ] = nr_read_queues; + affd->nr_sets = nr_read_queues ? 2 : 1; } static int nvme_setup_irqs(struct nvme_dev *dev, unsigned int nr_io_queues) @@ -2083,10 +2084,9 @@ static int nvme_setup_irqs(struct nvme_dev *dev, unsigned int nr_io_queues) struct pci_dev *pdev = to_pci_dev(dev->dev); struct irq_affinity affd = { .pre_vectors = 1, - .nr_sets = 2, + .calc_sets = nvme_calc_irq_sets, + .priv = dev, }; - unsigned int *irq_sets = affd.set_size; - int result = 0; unsigned int irq_queues, this_p_queues; /* @@ -2102,51 +2102,12 @@ static int nvme_setup_irqs(struct nvme_dev *dev, unsigned int nr_io_queues) } dev->io_queues[HCTX_TYPE_POLL] = this_p_queues; - /* - * For irq sets, we have to ask for minvec == maxvec. This passes - * any reduction back to us, so we can adjust our queue counts and - * IRQ vector needs. - */ - do { - nvme_calc_io_queues(dev, irq_queues); - irq_sets[0] = dev->io_queues[HCTX_TYPE_DEFAULT]; - irq_sets[1] = dev->io_queues[HCTX_TYPE_READ]; - if (!irq_sets[1]) - affd.nr_sets = 1; - - /* - * If we got a failure and we're down to asking for just - * 1 + 1 queues, just ask for a single vector. We'll share - * that between the single IO queue and the admin queue. - * Otherwise, we assign one independent vector to admin queue. - */ - if (irq_queues > 1) - irq_queues = irq_sets[0] + irq_sets[1] + 1; + /* Initialize for the single interrupt case */ + dev->io_queues[HCTX_TYPE_DEFAULT] = 1; + dev->io_queues[HCTX_TYPE_READ] = 0; - result = pci_alloc_irq_vectors_affinity(pdev, irq_queues, - irq_queues, - PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd); - - /* - * Need to reduce our vec counts. If we get ENOSPC, the - * platform should support mulitple vecs, we just need - * to decrease our ask. If we get EINVAL, the platform - * likely does not. Back down to ask for just one vector. - */ - if (result == -ENOSPC) { - irq_queues--; - if (!irq_queues) - return result; - continue; - } else if (result == -EINVAL) { - irq_queues = 1; - continue; - } else if (result <= 0) - return -EIO; - break; - } while (1); - - return result; + return pci_alloc_irq_vectors_affinity(pdev, 1, irq_queues, + PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY, &affd); } static void nvme_disable_io_queues(struct nvme_dev *dev) @@ -3019,6 +2980,7 @@ static struct pci_driver nvme_driver = { static int __init nvme_init(void) { + BUILD_BUG_ON(IRQ_AFFINITY_MAX_SETS < 2); return pci_register_driver(&nvme_driver); } -- cgit