linux/arch/sparc/kernel/cpumap.h

#ifndef _CPUMAP_H
#define _CPUMAP_H

#ifdef CONFIG_SMP
void cpu_map_rebuild(void);
int map_to_cpu(unsigned int index);
#define cpu_map_init() cpu_map_rebuild()
#else
#define cpu_map_init() do {} while (0)
static inline int map_to_cpu(unsigned int index)
{
	return raw_smp_processor_id();
}
#endif

#endif
sparc64: fix and optimize irq distribution irq_choose_cpu() should compare the affinity mask against cpu_online_map rather than CPU_MASK_ALL, since irq_select_affinity() sets the interrupt's affinity mask to cpu_online_map "and" CPU_MASK_ALL (which ends up being just cpu_online_map). The mask comparison in irq_choose_cpu() will always fail since the two masks are not the same. So the CPU chosen is the first CPU in the intersection of cpu_online_map and CPU_MASK_ALL, which is always CPU0. That means all interrupts are reassigned to CPU0... Distributing interrupts to CPUs in a linearly increasing round robin fashion is not optimal for the UltraSPARC T1/T2. Also, the irq_rover in irq_choose_cpu() causes an interrupt to be assigned to a different processor each time the interrupt is allocated and released. This may lead to an unbalanced distribution over time. A static mapping of interrupts to processors is done to optimize and balance interrupt distribution. For the T1/T2, interrupts are spread to different cores first, and then to strands within a core. The following is some benchmarks showing the effects of interrupt distribution on a T2. The test was done with iperf using a pair of T5220 boxes, each with a 10GBe NIU (XAUI) connected back to back. TCP \| Stock Linear RR IRQ Optimized IRQ Streams \| 2.6.30-rc5 Distribution Distribution \| GBits/sec GBits/sec GBits/sec --------+----------------------------------------- 1 0.839 0.862 0.868 8 1.16 4.96 5.88 16 1.15 6.40 8.04 100 1.09 7.28 8.68 Signed-off-by: Hong H. Pham <hong.pham@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net> 2009-06-04 17:10:11 +08:00			`#ifndef _CPUMAP_H`
			`#define _CPUMAP_H`

			`#ifdef CONFIG_SMP`
sparc: drop use of extern for prototypes in arch/sparc/* Drop the remaining uses of extern for prototypes in .h files in the sparc specific part of the kernel tree. Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: David S. Miller <davem@davemloft.net> 2014-05-17 05:25:51 +08:00			`void cpu_map_rebuild(void);`
			`int map_to_cpu(unsigned int index);`
sparc64: fix and optimize irq distribution irq_choose_cpu() should compare the affinity mask against cpu_online_map rather than CPU_MASK_ALL, since irq_select_affinity() sets the interrupt's affinity mask to cpu_online_map "and" CPU_MASK_ALL (which ends up being just cpu_online_map). The mask comparison in irq_choose_cpu() will always fail since the two masks are not the same. So the CPU chosen is the first CPU in the intersection of cpu_online_map and CPU_MASK_ALL, which is always CPU0. That means all interrupts are reassigned to CPU0... Distributing interrupts to CPUs in a linearly increasing round robin fashion is not optimal for the UltraSPARC T1/T2. Also, the irq_rover in irq_choose_cpu() causes an interrupt to be assigned to a different processor each time the interrupt is allocated and released. This may lead to an unbalanced distribution over time. A static mapping of interrupts to processors is done to optimize and balance interrupt distribution. For the T1/T2, interrupts are spread to different cores first, and then to strands within a core. The following is some benchmarks showing the effects of interrupt distribution on a T2. The test was done with iperf using a pair of T5220 boxes, each with a 10GBe NIU (XAUI) connected back to back. TCP \| Stock Linear RR IRQ Optimized IRQ Streams \| 2.6.30-rc5 Distribution Distribution \| GBits/sec GBits/sec GBits/sec --------+----------------------------------------- 1 0.839 0.862 0.868 8 1.16 4.96 5.88 16 1.15 6.40 8.04 100 1.09 7.28 8.68 Signed-off-by: Hong H. Pham <hong.pham@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net> 2009-06-04 17:10:11 +08:00			`#define cpu_map_init() cpu_map_rebuild()`
			`#else`
			`#define cpu_map_init() do {} while (0)`
			`static inline int map_to_cpu(unsigned int index)`
			`{`
			`return raw_smp_processor_id();`
			`}`
			`#endif`

			`#endif`