From b525903c254dab2491410f0f23707691b7c2c317 Mon Sep 17 00:00:00 2001 From: Julien Thierry Date: Thu, 31 Jan 2019 14:53:58 +0000 Subject: genirq: Provide basic NMI management for interrupt lines Add functionality to allocate interrupt lines that will deliver IRQs as Non-Maskable Interrupts. These allocations are only successful if the irqchip provides the necessary support and allows NMI delivery for the interrupt line. Interrupt lines allocated for NMI delivery must be enabled/disabled through enable_nmi/disable_nmi_nosync to keep their state consistent. To treat a PERCPU IRQ as NMI, the interrupt must not be shared nor threaded, the irqchip directly managing the IRQ must be the root irqchip and the irqchip cannot be behind a slow bus. Signed-off-by: Julien Thierry Reviewed-by: Marc Zyngier Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Marc Zyngier Signed-off-by: Marc Zyngier --- kernel/irq/internals.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/irq/internals.h') diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index ca6afa267070..2a77cdd27ca9 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -49,6 +49,7 @@ enum { * IRQS_WAITING - irq is waiting * IRQS_PENDING - irq is pending and replayed later * IRQS_SUSPENDED - irq is suspended + * IRQS_NMI - irq line is used to deliver NMIs */ enum { IRQS_AUTODETECT = 0x00000001, @@ -60,6 +61,7 @@ enum { IRQS_PENDING = 0x00000200, IRQS_SUSPENDED = 0x00000800, IRQS_TIMINGS = 0x00001000, + IRQS_NMI = 0x00002000, }; #include "debug.h" -- cgit From 1136b0728969901a091f0471968b2b76ed14d9ad Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Fri, 8 Feb 2019 14:48:03 +0100 Subject: genirq: Avoid summation loops for /proc/stat Waiman reported that on large systems with a large amount of interrupts the readout of /proc/stat takes a long time to sum up the interrupt statistics. In principle this is not a problem. but for unknown reasons some enterprise quality software reads /proc/stat with a high frequency. The reason for this is that interrupt statistics are accounted per cpu. So the /proc/stat logic has to sum up the interrupt stats for each interrupt. This can be largely avoided for interrupts which are not marked as 'PER_CPU' interrupts by simply adding a per interrupt summation counter which is incremented along with the per interrupt per cpu counter. The PER_CPU interrupts need to avoid that and use only per cpu accounting because they share the interrupt number and the interrupt descriptor and concurrent updates would conflict or require unwanted synchronization. Reported-by: Waiman Long Signed-off-by: Thomas Gleixner Reviewed-by: Waiman Long Reviewed-by: Marc Zyngier Reviewed-by: Davidlohr Bueso Cc: Matthew Wilcox Cc: Andrew Morton Cc: Alexey Dobriyan Cc: Kees Cook Cc: linux-fsdevel@vger.kernel.org Cc: Davidlohr Bueso Cc: Miklos Szeredi Cc: Daniel Colascione Cc: Dave Chinner Cc: Randy Dunlap Link: https://lkml.kernel.org/r/20190208135020.925487496@linutronix.de 8<------------- v2: Undo the unintentional layout change of struct irq_desc. include/linux/irqdesc.h | 1 + kernel/irq/chip.c | 12 ++++++++++-- kernel/irq/internals.h | 8 +++++++- kernel/irq/irqdesc.c | 7 ++++++- 4 files changed, 24 insertions(+), 4 deletions(-) --- kernel/irq/internals.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'kernel/irq/internals.h') diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index ca6afa267070..e74e7eea76cf 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -242,12 +242,18 @@ static inline void irq_state_set_masked(struct irq_desc *desc) #undef __irqd_to_state -static inline void kstat_incr_irqs_this_cpu(struct irq_desc *desc) +static inline void __kstat_incr_irqs_this_cpu(struct irq_desc *desc) { __this_cpu_inc(*desc->kstat_irqs); __this_cpu_inc(kstat.irqs_sum); } +static inline void kstat_incr_irqs_this_cpu(struct irq_desc *desc) +{ + __kstat_incr_irqs_this_cpu(desc); + desc->tot_count++; +} + static inline int irq_desc_get_node(struct irq_desc *desc) { return irq_common_data_get_node(&desc->irq_common_data); -- cgit