From 95c33a64f203be444954a1e1d855a4820c4f0efa Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 17 May 2026 22:01:38 +0200 Subject: genirq/proc: Avoid formatting zero counts in /proc/interrupts A large portion of interrupt count entries are zero. There is no point in formatting the zero value as it is way cheeper to just emit a constant string. Collect the number of consecutive zero counts and emit them in one go before a non-zero count and at the end of the line. Signed-off-by: Thomas Gleixner Tested-by: Michael Kelley Reviewed-by: Dmitry Ilvokhin Reviewed-by: Radu Rendec Reviewed-by: Shrikanth Hegde Link: https://patch.msgid.link/20260517194931.034728540@kernel.org --- include/linux/interrupt.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 6cd26ffb0505..3bf969ad8fe0 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -864,6 +864,7 @@ static inline void init_irq_proc(void) struct seq_file; int show_interrupts(struct seq_file *p, void *v); int arch_show_interrupts(struct seq_file *p, int prec); +void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts); extern int early_irq_init(void); extern int arch_probe_nr_irqs(void); -- cgit v1.2.3 From 0179464391af9a01b911f441d2dda42ea253dfbd Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 17 May 2026 22:01:43 +0200 Subject: genirq/proc: Utilize irq_desc::tot_count to avoid evaluation Interrupts which are not marked per CPU increment not only the per CPU statistics, but also the accumulation counter irq_desc::tot_count. Change the counter to type unsigned long so it does not produce sporadic zeros due to wrap arounds on 64-bit machines and do a quick check for non per CPU interrupts. If the counter is zero, then simply emit a full set of zero strings. That spares the evaluation of the per CPU counters completely for interrupts with zero events. Signed-off-by: Thomas Gleixner Tested-by: Michael Kelley Reviewed-by: Dmitry Ilvokhin Reviewed-by: Radu Rendec Link: https://patch.msgid.link/20260517194931.115522199@kernel.org --- include/linux/irqdesc.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h index dae9a9b93665..1058786d76eb 100644 --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -52,8 +52,8 @@ struct irq_redirect { * @depth: disable-depth, for nested irq_disable() calls * @wake_depth: enable depth, for multiple irq_set_irq_wake() callers * @tot_count: stats field for non-percpu irqs - * @irq_count: stats field to detect stalled irqs * @last_unhandled: aging timer for unhandled count + * @irq_count: stats field to detect stalled irqs * @irqs_unhandled: stats field for spurious unhandled interrupts * @threads_handled: stats field for deferred spurious detection of threaded handlers * @threads_handled_last: comparator field for deferred spurious detection of threaded handlers @@ -87,9 +87,9 @@ struct irq_desc { unsigned int core_internal_state__do_not_mess_with_it; unsigned int depth; /* nested irq disables */ unsigned int wake_depth; /* nested wake enables */ - unsigned int tot_count; - unsigned int irq_count; /* For detecting broken IRQs */ + unsigned long tot_count; unsigned long last_unhandled; /* Aging timer for unhandled count */ + unsigned int irq_count; /* For detecting broken IRQs */ unsigned int irqs_unhandled; atomic_t threads_handled; int threads_handled_last; -- cgit v1.2.3 From 4892e5e71ec9c942293cea7fd26e0c76179211ed Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 17 May 2026 22:02:19 +0200 Subject: genirq: Cache the condition for /proc/interrupts exposure show_interrupts() evaluates a boatload of conditions to establish whether it should expose an interrupt in /proc/interrupts or not. That can be simplified by caching the condition in an internal status flag, which is updated when one of the relevant inputs changes. The irq_desc::kstat_irq check is dropped because visible interrupt descriptors always have a valid pointer. As a result the number of instructions and branches for reading /proc/interrupts is reduced significantly. Signed-off-by: Thomas Gleixner Tested-by: Michael Kelley Reviewed-by: Dmitry Ilvokhin Reviewed-by: Radu Rendec Link: https://patch.msgid.link/20260517194931.680943749@kernel.org --- include/linux/irq.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/irq.h b/include/linux/irq.h index efa514ee562f..f485369b1b4f 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -103,6 +103,7 @@ enum { IRQ_DISABLE_UNLAZY = (1 << 19), IRQ_HIDDEN = (1 << 20), IRQ_NO_DEBUG = (1 << 21), + IRQ_RESERVED = (1 << 22), }; #define IRQF_MODIFY_MASK \ -- cgit v1.2.3 From 1d9c4745bfb6773712751f5068c23ebad9cd30a0 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 17 May 2026 22:02:34 +0200 Subject: genirq: Add rcuref count to struct irq_desc Prepare for a smarter iterator for /proc/interrupts so that the next interrupt descriptor can be cached after lookup. Signed-off-by: Thomas Gleixner Tested-by: Michael Kelley Reviewed-by: Dmitry Ilvokhin Link: https://patch.msgid.link/20260517194931.917415190@kernel.org --- include/linux/irqdesc.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h index 1058786d76eb..8080db17c1b1 100644 --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -70,6 +70,7 @@ struct irq_redirect { * IRQF_NO_SUSPEND set * @force_resume_depth: number of irqactions on a irq descriptor with * IRQF_FORCE_RESUME set + * @refcnt: Reference count mainly for /proc/interrupts * @rcu: rcu head for delayed free * @kobj: kobject used to represent this struct in sysfs * @request_mutex: mutex to protect request/free before locking desc->lock @@ -119,6 +120,7 @@ struct irq_desc { struct dentry *debugfs_file; const char *dev_name; #endif + rcuref_t refcnt; #ifdef CONFIG_SPARSE_IRQ struct rcu_head rcu; struct kobject kobj; -- cgit v1.2.3