Now when per-cpu printk buffers are gone, there's no need to have printk
flags or printk irq_work per cpu. Just make printk_pending a single
variable operated by atomic operations and have single unbound irq work
doing the waking and printing. This has an advantage that any cpu can do the
printing / wakeup work thus lowering the latency of printing and better
distributing the printing work over cpus.
Signed-off-by: Jan Kara <j...@suse.cz>
---
kernel/printk/printk.c | 47 ++++++++++++++++++++++++++---------------------
1 file changed, 26 insertions(+), 21 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index e97971b..d5ee3d0 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2486,36 +2486,41 @@ late_initcall(printk_late_init);
/*
* Delayed printk version, for scheduler-internal messages:
*/
-#define PRINTK_PENDING_WAKEUP 0x01
-#define PRINTK_PENDING_OUTPUT 0x02
+#define PRINTK_PENDING_WAKEUP 0
+#define PRINTK_PENDING_OUTPUT 1
-static DEFINE_PER_CPU(int, printk_pending);
+static unsigned long printk_pending;
-static void wake_up_klogd_work_func(struct irq_work *irq_work)
+static void printk_irq_work_func(struct irq_work *irq_work)
{
- int pending = __this_cpu_xchg(printk_pending, 0);
+ if (printk_pending) {
+ unsigned long pending = xchg(&printk_pending, 0);
- if (pending & PRINTK_PENDING_OUTPUT) {
- /* If trylock fails, someone else is doing the printing */
- if (console_trylock())
- console_unlock();
- }
+ if (test_bit(PRINTK_PENDING_OUTPUT, &pending)) {
+ /*
+ * If trylock fails, someone else is doing the
+ * printing
+ */
+ if (console_trylock())
+ console_unlock();
+ }
- if (pending & PRINTK_PENDING_WAKEUP)
- wake_up_interruptible(&log_wait);
+ if (test_bit(PRINTK_PENDING_WAKEUP, &pending))
+ wake_up_interruptible(&log_wait);
+ }
}
-static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
- .func = wake_up_klogd_work_func,
- .flags = IRQ_WORK_LAZY,
+static struct irq_work printk_irq_work = {
+ .func = printk_irq_work_func,
+ .flags = IRQ_WORK_UNBOUND,
};
void wake_up_klogd(void)
{
preempt_disable();
if (waitqueue_active(&log_wait)) {
- this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
- irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
+ set_bit(PRINTK_PENDING_WAKEUP, &printk_pending);
+ irq_work_queue(&printk_irq_work);
}
preempt_enable();
}
@@ -2529,8 +2534,8 @@ int printk_sched(const char *fmt, ...)
r = vprintk_emit(0, -2, NULL, 0, fmt, args);
va_end(args);
- __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
- irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
+ set_bit(PRINTK_PENDING_OUTPUT, &printk_pending);
+ irq_work_queue(&printk_irq_work);
return r;
}
@@ -2543,8 +2548,8 @@ void console_unlock(void)
{
if (__console_unlock()) {
/* Leave the rest of printing for a timer tick */
- __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
- irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
+ set_bit(PRINTK_PENDING_OUTPUT, &printk_pending);
+ irq_work_queue(&printk_irq_work);
}
}
EXPORT_SYMBOL(console_unlock);
--
1.8.1.4
--
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