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Subject[Patch 13 of 17] cpumask v4 - Simplify some sparc64 cpumask loop code
mask13-cpumask-sparc-simplify - Simplify some sparc64 cpumask loop code
Make use of for_each_cpu_mask() macro to simplify and optimize
a couple of sparc64 per-CPU loops. This code change has _not_
been tested or reviewed. Feedback welcome. There is non-trivial
risk that I still don't understand the logic here.

Index: 2.6.5.bitmap/arch/sparc64/kernel/smp.c
===================================================================
--- 2.6.5.bitmap.orig/arch/sparc64/kernel/smp.c 2004-04-05 02:41:32.000000000 -0700
+++ 2.6.5.bitmap/arch/sparc64/kernel/smp.c 2004-04-08 04:18:02.000000000 -0700
@@ -406,14 +406,8 @@
int i;

__asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));
- for (i = 0; i < NR_CPUS; i++) {
- if (cpu_isset(i, mask)) {
- spitfire_xcall_helper(data0, data1, data2, pstate, i);
- cpu_clear(i, mask);
- if (cpus_empty(mask))
- break;
- }
- }
+ for_each_cpu_mask(i, mask)
+ spitfire_xcall_helper(data0, data1, data2, pstate, i);
}

/* Cheetah now allows to send the whole 64-bytes of data in the interrupt
@@ -456,25 +450,19 @@

nack_busy_id = 0;
{
- cpumask_t work_mask = mask;
int i;

- for (i = 0; i < NR_CPUS; i++) {
- if (cpu_isset(i, work_mask)) {
- u64 target = (i << 14) | 0x70;
-
- if (!is_jalapeno)
- target |= (nack_busy_id << 24);
- __asm__ __volatile__(
- "stxa %%g0, [%0] %1\n\t"
- "membar #Sync\n\t"
- : /* no outputs */
- : "r" (target), "i" (ASI_INTR_W));
- nack_busy_id++;
- cpu_clear(i, work_mask);
- if (cpus_empty(work_mask))
- break;
- }
+ for_each_cpu_mask(i, mask) {
+ u64 target = (i << 14) | 0x70;
+
+ if (!is_jalapeno)
+ target |= (nack_busy_id << 24);
+ __asm__ __volatile__(
+ "stxa %%g0, [%0] %1\n\t"
+ "membar #Sync\n\t"
+ : /* no outputs */
+ : "r" (target), "i" (ASI_INTR_W));
+ nack_busy_id++;
}
}

@@ -507,7 +495,6 @@
printk("CPU[%d]: mondo stuckage result[%016lx]\n",
smp_processor_id(), dispatch_stat);
} else {
- cpumask_t work_mask = mask;
int i, this_busy_nack = 0;

/* Delay some random time with interrupts enabled
@@ -518,22 +505,17 @@
/* Clear out the mask bits for cpus which did not
* NACK us.
*/
- for (i = 0; i < NR_CPUS; i++) {
- if (cpu_isset(i, work_mask)) {
- u64 check_mask;
-
- if (is_jalapeno)
- check_mask = (0x2UL << (2*i));
- else
- check_mask = (0x2UL <<
- this_busy_nack);
- if ((dispatch_stat & check_mask) == 0)
- cpu_clear(i, mask);
- this_busy_nack += 2;
- cpu_clear(i, work_mask);
- if (cpus_empty(work_mask))
- break;
- }
+ for_each_cpu_mask(i, mask) {
+ u64 check_mask;
+
+ if (is_jalapeno)
+ check_mask = (0x2UL << (2*i));
+ else
+ check_mask = (0x2UL <<
+ this_busy_nack);
+ if ((dispatch_stat & check_mask) == 0)
+ cpu_clear(i, mask);
+ this_busy_nack += 2;
}

goto retry;

--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@sgi.com> 1.650.933.1373
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