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Subject[patch] Make prof_counter use per-cpu areas patch 1/4 -- x86 arch
Hi,
Here's a patchset to make prof_counter use percpu area infrastructure.
Right now, prof_counter is a NR_CPUS array which gets modified every
local timer interrupt causing cacheline ping-pong for i386, ppc, x86_64 and
sparc arches. Other arches have made this var truly per-cpu.

This one's for i386 (voyager included).

Thanks,
Kiran


diff -ruN -X dontdiff linux-2.5.55/arch/i386/kernel/apic.c prof_counter-2.5.54/arch/i386/kernel/apic.c
--- linux-2.5.55/arch/i386/kernel/apic.c Thu Jan 9 09:34:27 2003
+++ prof_counter-2.5.54/arch/i386/kernel/apic.c Fri Jan 10 13:02:06 2003
@@ -52,7 +52,7 @@

int prof_multiplier[NR_CPUS] = { 1, };
int prof_old_multiplier[NR_CPUS] = { 1, };
-int prof_counter[NR_CPUS] = { 1, };
+DEFINE_PER_CPU(int, prof_counter) = 1;

int get_maxlvt(void)
{
@@ -997,7 +997,7 @@

x86_do_profile(regs);

- if (--prof_counter[cpu] <= 0) {
+ if (--per_cpu(prof_counter, cpu) <= 0) {
/*
* The multiplier may have changed since the last time we got
* to this point as a result of the user writing to
@@ -1006,10 +1006,12 @@
*
* Interrupts are already masked off at this point.
*/
- prof_counter[cpu] = prof_multiplier[cpu];
- if (prof_counter[cpu] != prof_old_multiplier[cpu]) {
- __setup_APIC_LVTT(calibration_result/prof_counter[cpu]);
- prof_old_multiplier[cpu] = prof_counter[cpu];
+ per_cpu(prof_counter, cpu) = prof_multiplier[cpu];
+ if (per_cpu(prof_counter, cpu) != prof_old_multiplier[cpu]) {
+ __setup_APIC_LVTT(
+ calibration_result/
+ per_cpu(prof_counter, cpu));
+ prof_old_multiplier[cpu] = per_cpu(prof_counter, cpu);
}

#ifdef CONFIG_SMP
diff -ruN -X dontdiff linux-2.5.55/arch/i386/kernel/smpboot.c prof_counter-2.5.54/arch/i386/kernel/smpboot.c
--- linux-2.5.55/arch/i386/kernel/smpboot.c Thu Jan 9 09:34:14 2003
+++ prof_counter-2.5.54/arch/i386/kernel/smpboot.c Fri Jan 10 13:52:02 2003
@@ -937,7 +937,7 @@

extern int prof_multiplier[NR_CPUS];
extern int prof_old_multiplier[NR_CPUS];
-extern int prof_counter[NR_CPUS];
+DECLARE_PER_CPU(int, prof_counter);

static int boot_cpu_logical_apicid;
/* Where the IO area was mapped on multiquad, always 0 otherwise */
@@ -955,7 +955,7 @@
*/

for (cpu = 0; cpu < NR_CPUS; cpu++) {
- prof_counter[cpu] = 1;
+ per_cpu(prof_counter, cpu) = 1;
prof_old_multiplier[cpu] = 1;
prof_multiplier[cpu] = 1;
}
diff -ruN -X dontdiff linux-2.5.55/arch/i386/mach-voyager/voyager_smp.c prof_counter-2.5.54/arch/i386/mach-voyager/voyager_smp.c
--- linux-2.5.55/arch/i386/mach-voyager/voyager_smp.c Thu Jan 9 09:34:00 2003
+++ prof_counter-2.5.54/arch/i386/mach-voyager/voyager_smp.c Fri Jan 10 13:53:14 2003
@@ -236,7 +236,7 @@
/* The per cpu profile stuff - used in smp_local_timer_interrupt */
static unsigned int prof_multiplier[NR_CPUS] __cacheline_aligned = { 1, };
static unsigned int prof_old_multiplier[NR_CPUS] __cacheline_aligned = { 1, };
-static unsigned int prof_counter[NR_CPUS] __cacheline_aligned = { 1, };
+static DEFINE_PER_CPU(unsigned int, prof_counter) = 1;

/* the map used to check if a CPU has booted */
static __u32 cpu_booted_map;
@@ -393,7 +393,7 @@

/* initialize the CPU structures (moved from smp_boot_cpus) */
for(i=0; i<NR_CPUS; i++) {
- prof_counter[i] = 1;
+ per_cpu(prof_counter, i) = 1;
prof_old_multiplier[i] = 1;
prof_multiplier[i] = 1;
cpu_irq_affinity[i] = ~0;
@@ -1312,7 +1312,7 @@

x86_do_profile(regs);

- if (--prof_counter[cpu] <= 0) {
+ if (--per_cpu(prof_counter, cpu) <= 0) {
/*
* The multiplier may have changed since the last time we got
* to this point as a result of the user writing to
@@ -1321,10 +1321,10 @@
*
* Interrupts are already masked off at this point.
*/
- prof_counter[cpu] = prof_multiplier[cpu];
- if (prof_counter[cpu] != prof_old_multiplier[cpu]) {
+ per_cpu(prof_counter,cpu) = prof_multiplier[cpu];
+ if (per_cpu(prof_counter, cpu) != prof_old_multiplier[cpu]) {
/* FIXME: need to update the vic timer tick here */
- prof_old_multiplier[cpu] = prof_counter[cpu];
+ prof_old_multiplier[cpu] = per_cpu(prof_counter, cpu);
}

update_process_times(user_mode(regs));
-
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