by Linus, please apply.
Moves the ksoftirqd pointers out of the irq_stat struct, and use a
normal per-cpu variable. It's not that time critical, nor referenced
in assembler. This moves us closer to making irq_stat a per-cpu variable.
Because some archs have hardcoded asm references to offsets in this
structure, I haven't touched non-x86. The __ksoftirqd_task field
is unused in other archs, too.
Name: ksoftirqds in per-cpu variable
Author: Rusty Russell
Status: Tested on 2.5.74
Depends: Percpu/irq_syscall_count_removal.patch.gz
D: Moves the ksoftirqd pointers out of the irq_stat struct, and use a
D: normal per-cpu variable. It's not that time critical, nor referenced
D: in assembler. This moves us closer to making irq_stat a per-cpu variable.
D:
D: Because some archs have hardcoded asm references to offsets in this
D: structure, I haven't touched non-x86. The __ksoftirqd_task field
D: is unused in other archs, too.
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .5097-2.5.73-bk8-ksoftirqd_percpu.pre/include/asm-i386/hardirq.h .5097-2.5.73-bk8-ksoftirqd_percpu/include/asm-i386/hardirq.h
--- .5097-2.5.73-bk8-ksoftirqd_percpu.pre/include/asm-i386/hardirq.h 2003-07-01 15:26:58.000000000 +1000
typedef struct {
unsigned int __softirq_pending;
- struct task_struct * __ksoftirqd_task; /* waitqueue is too large */
unsigned long idle_timestamp;
unsigned int __nmi_count; /* arch dependent */
unsigned int apic_timer_irqs; /* arch dependent */
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .5097-2.5.73-bk8-ksoftirqd_percpu.pre/include/linux/irq_cpustat.h .5097-2.5.73-bk8-ksoftirqd_percpu/include/linux/irq_cpustat.h
--- .5097-2.5.73-bk8-ksoftirqd_percpu.pre/include/linux/irq_cpustat.h 2003-07-01 15:26:58.000000000 +1000
/* arch independent irq_stat fields */
#define softirq_pending(cpu) __IRQ_STAT((cpu), __softirq_pending)
#define local_softirq_pending() softirq_pending(smp_processor_id())
-#define ksoftirqd_task(cpu) __IRQ_STAT((cpu), __ksoftirqd_task)
-#define local_ksoftirqd_task() ksoftirqd_task(smp_processor_id())
/* arch dependent irq_stat fields */
#define nmi_count(cpu) __IRQ_STAT((cpu), __nmi_count) /* i386 */
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .5097-2.5.73-bk8-ksoftirqd_percpu.pre/kernel/softirq.c .5097-2.5.73-bk8-ksoftirqd_percpu/kernel/softirq.c
--- .5097-2.5.73-bk8-ksoftirqd_percpu.pre/kernel/softirq.c 2003-06-15 11:30:11.000000000 +1000
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/notifier.h>
+#include <linux/percpu.h>
#include <linux/cpu.h>
static struct softirq_action softirq_vec[32] __cacheline_aligned_in_smp;
+static DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
+
/*
* we cannot loop indefinitely here to avoid userspace starvation,
* but we also don't want to introduce a worst case 1/HZ latency
* to the pending events, so lets the scheduler to balance
* the softirq load for us.
*/
-static inline void wakeup_softirqd(unsigned cpu)
+static inline void wakeup_softirqd(void)
{
- struct task_struct * tsk = ksoftirqd_task(cpu);
+ /* Interrupts are disabled: no need to stop preemption */
+ struct task_struct *tsk = __get_cpu_var(ksoftirqd);
if (tsk && tsk->state != TASK_RUNNING)
goto restart;
}
if (pending)
- wakeup_softirqd(smp_processor_id());
+ wakeup_softirqd();
__local_bh_enable();
}
* schedule the softirq soon.
*/
if (!in_interrupt())
- wakeup_softirqd(cpu);
+ wakeup_softirqd();
}
__set_current_state(TASK_INTERRUPTIBLE);
mb();
- local_ksoftirqd_task() = current;
+ __get_cpu_var(ksoftirqd) = current;
for (;;) {
return NOTIFY_BAD;
}
- while (!ksoftirqd_task(hotcpu))
+ while (!per_cpu(ksoftirqd, hotcpu))
yield();
}
return NOTIFY_OK;
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
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