path: root/kernel/irq/internals.h
diff options
authorThomas Gleixner <tglx@linutronix.de>2019-02-08 14:48:03 +0100
committerThomas Gleixner <tglx@linutronix.de>2019-02-10 21:34:45 +0100
commit1136b0728969901a091f0471968b2b76ed14d9ad (patch)
tree636c5fbc5e7b28cbb6454323dde1cf9775a4c9a1 /kernel/irq/internals.h
parent347253c42d7c673aa2a659d756bc7ff893459247 (diff)
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 <longman@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Waiman Long <longman@redhat.com> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Cc: Matthew Wilcox <willy@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: linux-fsdevel@vger.kernel.org Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Daniel Colascione <dancol@google.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Randy Dunlap <rdunlap@infradead.org> 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(-)
Diffstat (limited to 'kernel/irq/internals.h')
1 files changed, 7 insertions, 1 deletions
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)
+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);