From: jun qian <[email protected]>
Add a function interface to end softirq process
Signed-off-by: jun qian <[email protected]>
---
kernel/softirq.c | 44 +++++++++++++++++++++++++-------------------
1 file changed, 25 insertions(+), 19 deletions(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 0db77ab..5a627cd 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -198,22 +198,6 @@ void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
}
EXPORT_SYMBOL(__local_bh_enable_ip);
-/*
- * We restart softirq processing for at most MAX_SOFTIRQ_RESTART times,
- * but break the loop if need_resched() is set or after 2 ms.
- * The MAX_SOFTIRQ_TIME provides a nice upper bound in most cases, but in
- * certain cases, such as stop_machine(), jiffies may cease to
- * increment and so we need the MAX_SOFTIRQ_RESTART limit as
- * well to make sure we eventually return from this method.
- *
- * These limits have been established via experimentation.
- * The two things to balance is latency against fairness -
- * we want to handle softirqs as soon as possible, but they
- * should not be able to lock up the box.
- */
-#define MAX_SOFTIRQ_TIME (2 * NSEC_PER_MSEC)
-#define MAX_SOFTIRQ_RESTART 10
-
#ifdef CONFIG_TRACE_IRQFLAGS
/*
* When we run softirqs from irq_exit() and thus on the hardirq stack we need
@@ -247,11 +231,34 @@ static inline void lockdep_softirq_end(bool in_hardirq)
static inline void lockdep_softirq_end(bool in_hardirq) { }
#endif
+/*
+ * We restart softirq processing but break the loop if need_resched() is
+ * set or after 2 ms. The MAX_SOFTIRQ_RESTART guarantees a loop termination
+ * if sched_clock() were ever to stall.
+ *
+ * These limits have been established via experimentation. The two things
+ * to balance is latency against fairness - we want to handle softirqs as
+ * soon as possible, but they should not be able to lock up the box.
+ */
+#define MAX_SOFTIRQ_TIME (2 * NSEC_PER_MSEC)
+#define MAX_SOFTIRQ_RESTART 10
+
+static inline bool __softirq_needs_break(u64 start)
+{
+ if (need_resched())
+ return true;
+
+ if (sched_clock() - start >= MAX_SOFTIRQ_TIME)
+ return true;
+
+ return false;
+}
+
asmlinkage __visible void __softirq_entry __do_softirq(void)
{
u64 start = sched_clock();
unsigned long old_flags = current->flags;
- int max_restart = MAX_SOFTIRQ_RESTART;
+ unsigned int max_restart = MAX_SOFTIRQ_RESTART;
struct softirq_action *h;
bool in_hardirq;
__u32 pending;
@@ -308,8 +315,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
pending = local_softirq_pending();
if (pending) {
- if (sched_clock() - start < MAX_SOFTIRQ_TIME && !need_resched() &&
- --max_restart)
+ if (!__softirq_needs_break(start) && --max_restart)
goto restart;
wakeup_softirqd();
--
1.8.3.1
On Tue, Sep 15 2020 at 19:56, qianjun kernel wrote:
> asmlinkage __visible void __softirq_entry __do_softirq(void)
> {
> u64 start = sched_clock();
> unsigned long old_flags = current->flags;
> - int max_restart = MAX_SOFTIRQ_RESTART;
> + unsigned int max_restart = MAX_SOFTIRQ_RESTART;
And this change is related to making the timeout check a function in
which way?
Thanks,
tglx
On Thu, Sep 24 2020 at 10:36, Thomas Gleixner wrote:
> On Tue, Sep 15 2020 at 19:56, qianjun kernel wrote:
>> asmlinkage __visible void __softirq_entry __do_softirq(void)
>> {
>> u64 start = sched_clock();
>> unsigned long old_flags = current->flags;
>> - int max_restart = MAX_SOFTIRQ_RESTART;
>> + unsigned int max_restart = MAX_SOFTIRQ_RESTART;
>
> And this change is related to making the timeout check a function in
> which way?
Aside of that looking at:
https://lore.kernel.org/r/[email protected]
Peter gave you a series of patches, granted they are untested and
lacking proper changelogs. But you go and repost them mostly unmodified
and taking authorship of them.
This not the way it works. You cannot claim authorship of something you
did not write yourself. See Documentation/process/ for detailed
explanation how to handle patches which you got from someone else.
Thanks,
tglx