From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.9]:37948 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932206AbcFNT73 (ORCPT ); Tue, 14 Jun 2016 15:59:29 -0400 From: Christoph Hellwig To: tglx@linutronix.de, axboe@fb.com Cc: linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors Date: Tue, 14 Jun 2016 21:58:59 +0200 Message-Id: <1465934346-20648-7-git-send-email-hch@lst.de> In-Reply-To: <1465934346-20648-1-git-send-email-hch@lst.de> References: <1465934346-20648-1-git-send-email-hch@lst.de> Sender: linux-pci-owner@vger.kernel.org List-ID: This is lifted from the blk-mq code and adopted to use the affinity mask concept just intruced in the irq handling code. Signed-off-by: Christoph Hellwig --- include/linux/interrupt.h | 11 +++++++++ kernel/irq/Makefile | 1 + kernel/irq/affinity.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 72 insertions(+) create mode 100644 kernel/irq/affinity.c diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 9fcabeb..12003c0 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -278,6 +278,9 @@ extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m); extern int irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify); +int irq_create_affinity_mask(struct cpumask **affinity_mask, + unsigned int *nr_vecs); + #else /* CONFIG_SMP */ static inline int irq_set_affinity(unsigned int irq, const struct cpumask *m) @@ -308,6 +311,14 @@ irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify) { return 0; } + +static inline int irq_create_affinity_mask(struct cpumask **affinity_mask, + unsigned int *nr_vecs) +{ + *affinity_mask = NULL; + *nr_vecs = 1; + return 0; +} #endif /* CONFIG_SMP */ /* diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile index 2ee42e9..1d3ee31 100644 --- a/kernel/irq/Makefile +++ b/kernel/irq/Makefile @@ -9,3 +9,4 @@ obj-$(CONFIG_GENERIC_IRQ_MIGRATION) += cpuhotplug.o obj-$(CONFIG_PM_SLEEP) += pm.o obj-$(CONFIG_GENERIC_MSI_IRQ) += msi.o obj-$(CONFIG_GENERIC_IRQ_IPI) += ipi.o +obj-$(CONFIG_SMP) += affinity.o diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c new file mode 100644 index 0000000..1daf8fb --- /dev/null +++ b/kernel/irq/affinity.c @@ -0,0 +1,60 @@ + +#include +#include +#include +#include + +static int get_first_sibling(unsigned int cpu) +{ + unsigned int ret; + + ret = cpumask_first(topology_sibling_cpumask(cpu)); + if (ret < nr_cpu_ids) + return ret; + return cpu; +} + +/* + * Take a map of online CPUs and the number of available interrupt vectors + * and generate an output cpumask suitable for spreading MSI/MSI-X vectors + * so that they are distributed as good as possible around the CPUs. If + * more vectors than CPUs are available we'll map one to each CPU, + * otherwise we map one to the first sibling of each socket. + * + * If there are more vectors than CPUs we will still only have one bit + * set per CPU, but interrupt code will keep on assining the vectors from + * the start of the bitmap until we run out of vectors. + */ +int irq_create_affinity_mask(struct cpumask **affinity_mask, + unsigned int *nr_vecs) +{ + unsigned int vecs = 0; + + if (*nr_vecs == 1) { + *affinity_mask = NULL; + return 0; + } + + *affinity_mask = kzalloc(cpumask_size(), GFP_KERNEL); + if (!*affinity_mask) + return -ENOMEM; + + if (*nr_vecs >= num_online_cpus()) { + cpumask_copy(*affinity_mask, cpu_online_mask); + } else { + unsigned int cpu; + + for_each_online_cpu(cpu) { + if (cpu == get_first_sibling(cpu)) { + cpumask_set_cpu(cpu, *affinity_mask); + vecs++; + } + + if (--(*nr_vecs) == 0) + break; + } + } + + *nr_vecs = vecs; + return 0; +} -- 2.1.4