mirror of
https://github.com/torvalds/linux.git
synced 2024-11-07 20:51:47 +00:00
280ff97494
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>
17 lines
320 B
C
17 lines
320 B
C
#ifndef _CPUMAP_H
|
|
#define _CPUMAP_H
|
|
|
|
#ifdef CONFIG_SMP
|
|
extern void cpu_map_rebuild(void);
|
|
extern 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
|