From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Reduce the softirq timeout when it is preempting an RT task.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Liu Jian <liujian56@xxxxxxxxxx>
---
kernel/softirq.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index e2cad5d108c8..baa08ae1604f 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -522,12 +522,12 @@ static inline void lockdep_softirq_end(bool in_hardirq) { }
#define MAX_SOFTIRQ_TIME (2 * NSEC_PER_MSEC)
#define MAX_SOFTIRQ_RESTART 10
-static inline bool __softirq_needs_break(u64 start)
+static inline bool __softirq_needs_break(u64 start, u64 timo)
{
if (need_resched())
return true;
- if (sched_clock() - start >= MAX_SOFTIRQ_TIME)
+ if (sched_clock() - start >= timo)
return true;
return false;
@@ -537,6 +537,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
{
unsigned int max_restart = MAX_SOFTIRQ_RESTART;
unsigned long old_flags = current->flags;
+ u64 timo = MAX_SOFTIRQ_TIME;
u64 start = sched_clock();
struct softirq_action *h;
unsigned long pending;
@@ -556,6 +557,9 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
in_hardirq = lockdep_softirq_start();
account_softirq_enter(current);
+ if (__this_cpu_read(ksoftirqd) != current && task_is_realtime(current))
+ timo >>= 2;
+
restart:
/* Reset the pending bitmask before enabling irqs */
set_softirq_pending(0);
@@ -583,7 +587,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
preempt_count_set(prev_count);
}
- if (pending && __softirq_needs_break(start))
+ if (pending && __softirq_needs_break(start, timo))
break;
}
@@ -596,7 +600,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
if (pending)
or_softirq_pending(pending);
else if ((pending = local_softirq_pending()) &&
- !__softirq_needs_break(start) &&
+ !__softirq_needs_break(start, timo) &&
--max_restart)
goto restart;
--
2.34.1
