This patch for 2.5.21 reduces the stack frame size of
arch/i386/kernel/nmi.c:check_nmi_watchdog() from 4096 bytes
in the worst case to 128 bytes. Linus, please apply.
The problem with the current code is that it copies the entire
irq_stat[] array, when only a single field (__nmi_count) is of
interest. The irq_stat_t element type is only 28 bytes, but it
is also ____cacheline_aligned, and that blows the array up to
4096 bytes on SMP P4 Xeons, 2048 bytes on SMP K7s, and 1024 bytes
on SMP P5/P6s. The patch reduces this to NR_CPUS*4==128 bytes.
If you approve this patch I'll also send one to Marcelo for 2.4.
/Mikael
diff -ruN linux-2.5.21/arch/i386/kernel/nmi.c linux-2.5.21.check-nmi/arch/i386/kernel/nmi.c
--- linux-2.5.21/arch/i386/kernel/nmi.c Mon Apr 15 00:32:51 2002
+++ linux-2.5.21.check-nmi/arch/i386/kernel/nmi.c Sun Jun 16 12:16:55 2002
@@ -72,18 +72,19 @@
int __init check_nmi_watchdog (void)
{
- irq_cpustat_t tmp[NR_CPUS];
+ unsigned int prev_nmi_count[NR_CPUS];
int j, cpu;
printk(KERN_INFO "testing NMI watchdog ... ");
- memcpy(tmp, irq_stat, sizeof(tmp));
+ for(j = 0; j < NR_CPUS; ++j)
+ prev_nmi_count[j] = irq_stat[j].__nmi_count;
sti();
mdelay((10*1000)/nmi_hz); // wait 10 ticks
for (j = 0; j < smp_num_cpus; j++) {
cpu = cpu_logical_map(j);
- if (nmi_count(cpu) - tmp[cpu].__nmi_count <= 5) {
+ if (nmi_count(cpu) - prev_nmi_count[cpu] <= 5) {
printk("CPU#%d: NMI appears to be stuck!\n", cpu);
return -1;
}
-
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This archive was generated by hypermail 2b29 : Sun Jun 23 2002 - 22:00:11 EST