Shrink shadow_flush_counts to a short array to save 8k of

Making allmodconfig will break the current build. This patch shrinks the per_cpu__shadow_flush_counts from 16k to 8k which frees enough space to allow allmodconfig to successfully complete.

---

I realize this is not as clean as it might be. We were concerned both about moving the shadow_flush_counts[] to be an allocation and then causing additional TLB (albeit slight) pressure. This seemed like a reasonable compromise. I don't think I personally have any additional time to put into this issue for this kernel release.

Robin

Index: reduce_per_cpu_usage/arch/ia64/kernel/smp.c
=================================--- reduce_per_cpu_usage.orig/arch/ia64/kernel/smp.c 2008-08-15 09:04:39.434143449 -0500
+++ reduce_per_cpu_usage/arch/ia64/kernel/smp.c 2008-08-15 09:10:22.436964745 -0500
@@ -58,7 +58,7 @@ static struct local_tlb_flush_counts {
unsigned int count;
} __attribute__((__aligned__(32))) local_tlb_flush_counts[NR_CPUS];

-static DEFINE_PER_CPU(unsigned int, shadow_flush_counts[NR_CPUS]) ____cacheline_aligned; +static DEFINE_PER_CPU(unsigned short, shadow_flush_counts[NR_CPUS]) ____cacheline_aligned;

#define IPI_CALL_FUNC 0
#define IPI_CPU_STOP 1
@@ -254,7 +254,7 @@ smp_local_flush_tlb(void)
void
smp_flush_tlb_cpumask(cpumask_t xcpumask)
{
- unsigned int *counts = __ia64_per_cpu_var(shadow_flush_counts);
+ unsigned short *counts = __ia64_per_cpu_var(shadow_flush_counts);
cpumask_t cpumask = xcpumask;
int mycpu, cpu, flush_mycpu = 0;

@@ -262,7 +262,7 @@ smp_flush_tlb_cpumask(cpumask_t xcpumask
mycpu = smp_processor_id();

for_each_cpu_mask(cpu, cpumask)
- counts[cpu] = local_tlb_flush_counts[cpu].count;
+ counts[cpu] = local_tlb_flush_counts[cpu].count & 0xffff;

mb();
for_each_cpu_mask(cpu, cpumask) {
@@ -276,7 +276,7 @@ smp_flush_tlb_cpumask(cpumask_t xcpumask
smp_local_flush_tlb();

for_each_cpu_mask(cpu, cpumask)
- while(counts[cpu] = local_tlb_flush_counts[cpu].count)
+ while(counts[cpu] = (local_tlb_flush_counts[cpu].count & 0xffff))
udelay(FLUSH_DELAY);

preempt_enable();