On Fri, May 5, 2023 at 7:25 PM Liu Jian <liujian56@xxxxxxxxxx> wrote:
>
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
>
> Replace the jiffies based timeout with a sched_clock() based one.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Liu Jian <liujian56@xxxxxxxxxx>
> ---
> kernel/softirq.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index bff5debf6ce6..59f16a9af5d1 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -27,6 +27,7 @@
> #include <linux/tick.h>
> #include <linux/irq.h>
> #include <linux/wait_bit.h>
> +#include <linux/sched/clock.h>
>
> #include <asm/softirq_stack.h>
>
> @@ -489,7 +490,7 @@ asmlinkage __visible void do_softirq(void)
> * we want to handle softirqs as soon as possible, but they
> * should not be able to lock up the box.
> */
> -#define MAX_SOFTIRQ_TIME msecs_to_jiffies(2)
> +#define MAX_SOFTIRQ_TIME (2 * NSEC_PER_MSEC)
I wonder if it affects those servers that set HZ to some different
values rather than 1000 as default.
Thanks,
Jason
> #define MAX_SOFTIRQ_RESTART 10
>
> #ifdef CONFIG_TRACE_IRQFLAGS
> @@ -527,9 +528,9 @@ static inline void lockdep_softirq_end(bool in_hardirq) { }
>
> asmlinkage __visible void __softirq_entry __do_softirq(void)
> {
> - unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
> unsigned long old_flags = current->flags;
> int max_restart = MAX_SOFTIRQ_RESTART;
> + u64 start = sched_clock();
> struct softirq_action *h;
> unsigned long pending;
> unsigned int vec_nr;
> @@ -584,7 +585,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
>
> pending = local_softirq_pending();
> if (pending) {
> - if (time_before(jiffies, end) && !need_resched() &&
> + if (sched_clock() - start < MAX_SOFTIRQ_TIME && !need_resched() &&
> --max_restart)
> goto restart;
>
> --
> 2.34.1
>
>
