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| author | Hong H. Pham <hong.pham@windriver.com> | 2009-06-04 11:10:11 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-06-16 13:56:28 +0200 |
| commit | 280ff97494e0fef4124bee5c52e39b23a18dd283 (patch) | |
| tree | e906ca3c5e0a6238882d181ab5b01fb3f40ba5df /arch/sparc/kernel/smp_64.c | |
| parent | sparc64: Use new dynamic per-cpu allocator. (diff) | |
| download | linux-280ff97494e0fef4124bee5c52e39b23a18dd283.tar.xz linux-280ff97494e0fef4124bee5c52e39b23a18dd283.zip | |
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>
Diffstat (limited to 'arch/sparc/kernel/smp_64.c')
| -rw-r--r-- | arch/sparc/kernel/smp_64.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c index 1de47d2169c8..cfb3d06058ff 100644 --- a/arch/sparc/kernel/smp_64.c +++ b/arch/sparc/kernel/smp_64.c @@ -48,6 +48,8 @@ #include <asm/ldc.h> #include <asm/hypervisor.h> +#include "cpumap.h" + int sparc64_multi_core __read_mostly; DEFINE_PER_CPU(cpumask_t, cpu_sibling_map) = CPU_MASK_NONE; @@ -1314,6 +1316,8 @@ int __cpu_disable(void) cpu_clear(cpu, cpu_online_map); ipi_call_unlock(); + cpu_map_rebuild(); + return 0; } |