[PATCH] Re: softirq buggy

Manfred Spraul
2001-04-08T21:36:45Z

[-- Attachment #1: Type: text/plain, Size: 377 bytes --]

I've attached a new patch:

* cpu_is_idle() moved to <linux/pm.h>
* function uninlined due to header dependencies
* cpu_is_idle() doesn't call do_softirq directly, instead the caller
returns to schedule()
* cpu_is_idle() exported for modules.
* docu updated.

I'd prefer to inline cpu_is_idle(), but optimizing the idle code path is
probably not that important ;-)

--
Manfred

[-- Attachment #2: patch-cpu-idle --]
[-- Type: text/plain, Size: 2940 bytes --]

// $Header$
// Kernel Version:
// VERSION = 2
// PATCHLEVEL = 4
// SUBLEVEL = 3
// EXTRAVERSION = -ac3
--- 2.4/include/linux/pm.h Thu Jan 4 23:50:47 2001
+++ build-2.4/include/linux/pm.h Sun Apr 8 21:02:02 2001
@@ -186,6 +186,8 @@
extern void (*pm_idle)(void);
extern void (*pm_power_off)(void);

+int cpu_is_idle(void);
+
#endif /* __KERNEL__ */

#endif /* _LINUX_PM_H */
--- 2.4/kernel/sched.c Sat Apr 7 22:02:27 2001
+++ build-2.4/kernel/sched.c Sun Apr 8 21:02:37 2001
@@ -1242,6 +1242,28 @@
sched_data->last_schedule = get_cycles();
}

+/**
+ * cpu_is_idle - helper function for idle functions
+ *
+ * pm_idle functions must call this function to verify that
+ * the cpu is really idle.
+ * The return value is valid until local interrupts are
+ * reenabled.
+ * Return values:
+ * 1: go into power saving mode.
+ * 0: cpu is not idle, return to schedule()
+ */
+int cpu_is_idle(void)
+{
+ if (current->need_resched)
+ return 0;
+
+ if (softirq_active(smp_processor_id()) & softirq_mask(smp_processor_id()))
+ return 0;
+
+ return 1;
+}
+
extern void init_timervecs (void);

void __init sched_init(void)
--- 2.4/kernel/ksyms.c Sat Apr 7 22:02:27 2001
+++ build-2.4/kernel/ksyms.c Sun Apr 8 21:42:48 2001
@@ -440,6 +440,7 @@
#endif
EXPORT_SYMBOL(kstat);
EXPORT_SYMBOL(nr_running);
+EXPORT_SYMBOL(cpu_is_idle);

/* misc */
EXPORT_SYMBOL(panic);
--- 2.4/arch/i386/kernel/process.c Thu Feb 22 22:28:52 2001
+++ build-2.4/arch/i386/kernel/process.c Sun Apr 8 21:25:23 2001
@@ -81,7 +81,7 @@
{
if (current_cpu_data.hlt_works_ok && !hlt_counter) {
__cli();
- if (!current->need_resched)
+ if (cpu_is_idle())
safe_halt();
else
__sti();
@@ -105,13 +105,10 @@
*/
oldval = xchg(&current->need_resched, -1);

- if (!oldval)
- asm volatile(
- "2:"
- "cmpl $-1, %0;"
- "rep; nop;"
- "je 2b;"
- : :"m" (current->need_resched));
+ if (!oldval) {
+ while(cpu_is_idle())
+ rep_nop();
+ }
}

/*
@@ -131,7 +128,7 @@
void (*idle)(void) = pm_idle;
if (!idle)
idle = default_idle;
- while (!current->need_resched)
+ while (cpu_is_idle())
idle();
schedule();
check_pgt_cache();
--- 2.4/drivers/acpi/cpu.c Sat Apr 7 22:02:01 2001
+++ build-2.4/drivers/acpi/cpu.c Sat Apr 7 23:55:17 2001
@@ -148,7 +148,7 @@
unsigned long diff;

__cli();
- if (current->need_resched)
+ if (!cpu_is_idle())
goto out;
if (acpi_bm_activity())
goto sleep2;
@@ -171,7 +171,7 @@
unsigned long diff;

__cli();
- if (current->need_resched)
+ if (!cpu_is_idle())
goto out;
if (acpi_bm_activity())
goto sleep2;
@@ -205,7 +205,7 @@
unsigned long diff;

__cli();
- if (current->need_resched)
+ if (!cpu_is_idle())
goto out;

time = acpi_read_pm_timer();
@@ -235,7 +235,7 @@
unsigned long diff;

__cli();
- if (current->need_resched)
+ if (!cpu_is_idle())
goto out;
time = acpi_read_pm_timer();
acpi_c1_count++;