for_each_online_cpu(cpu)
for_each_present_cpu(cpu)
void show_ipi_list(struct seq_file *p){	unsigned int cpu;	seq_puts(p, "IPI:");	for_each_online_cpu(cpu)		seq_printf(p, " %10lu", per_cpu(ipi_data, cpu).ipi_count);	seq_putc(p, '\n');}