[PATCH 4/4] tickless idle cpus: decrementer statistics - NOT MEANT FOR INCLUSION
Srivatsa Vaddagiri
vatsa at in.ibm.com
Fri Apr 7 16:32:56 EST 2006
This patch (a hack) provides some statistics of decrementer exception on
each CPU. I used this purely to verify that tickless feature is working.
Anton, would this be useful statistics to be exposed (maybe in
/proc/interrupts)? If so, I could work out a more cleaner way of
providing this statistics to user.
Signed-off-by: Srivatsa Vaddagiri <vatsa at in.ibm.com>
---
linux-2.6.17-rc1-root/arch/powerpc/kernel/time.c | 4 ++++
linux-2.6.17-rc1-root/fs/proc/proc_misc.c | 17 +++++++++++++++++
2 files changed, 21 insertions(+)
diff -puN arch/powerpc/kernel/time.c~stat arch/powerpc/kernel/time.c
--- linux-2.6.17-rc1/arch/powerpc/kernel/time.c~stat 2006-04-07 11:29:20.000000000 +0530
+++ linux-2.6.17-rc1-root/arch/powerpc/kernel/time.c 2006-04-07 11:29:20.000000000 +0530
@@ -757,6 +757,8 @@ void start_hz_timer(struct pt_regs *regs
static inline int clear_hzless_mask(void) { return 0;}
#endif
+DEFINE_PER_CPU(int, dec_ticks);
+
/*
* For iSeries shared processors, we have to let the hypervisor
* set the hardware decrementer. We set a virtual decrementer
@@ -780,6 +782,8 @@ void timer_interrupt(struct pt_regs * re
irq_enter();
+ __get_cpu_var(dec_ticks) += 1;
+
clear_hzless_mask();
profile_tick(CPU_PROFILING, regs);
diff -puN fs/proc/proc_misc.c~stat fs/proc/proc_misc.c
--- linux-2.6.17-rc1/fs/proc/proc_misc.c~stat 2006-04-07 11:29:20.000000000 +0530
+++ linux-2.6.17-rc1-root/fs/proc/proc_misc.c 2006-04-07 11:29:20.000000000 +0530
@@ -243,6 +243,22 @@ static int version_read_proc(char *page,
return proc_calc_metrics(page, start, off, count, eof, len);
}
+DECLARE_PER_CPU(int, dec_ticks);
+
+static int decrementer_read_proc(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ int len, cpu;
+ char *cp = page;
+
+ for_each_cpu(cpu)
+ cp += sprintf (cp, "%d ", per_cpu(dec_ticks, cpu));
+
+ len = cp - page;
+
+ return proc_calc_metrics(page, start, off, count, eof, len);
+}
+
extern struct seq_operations cpuinfo_op;
static int cpuinfo_open(struct inode *inode, struct file *file)
{
@@ -740,6 +756,7 @@ void __init proc_misc_init(void)
{"uptime", uptime_read_proc},
{"meminfo", meminfo_read_proc},
{"version", version_read_proc},
+ {"decrementer", decrementer_read_proc},
#ifdef CONFIG_PROC_HARDWARE
{"hardware", hardware_read_proc},
#endif
_
--
Regards,
vatsa
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