[PATCH] x86: printk_time to use tsc before cpu_clock is ready

Yinghai Lu
2008-08-27T07:40:35Z

so can get tsc value on printk at first.

for debug delay with big system with a lot of memory.

need to apply after
[PATCH] printk_time: prepare stub for using other than cpu_clock

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

---
arch/x86/kernel/cpu/common.c | 11 +++++++++++
arch/x86/kernel/cpu/common_64.c | 12 ++++++++++++
2 files changed, 23 insertions(+)

Index: linux-2.6/arch/x86/kernel/cpu/common.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/common.c
+++ linux-2.6/arch/x86/kernel/cpu/common.c
@@ -647,6 +647,15 @@ __setup("clearcpuid=", setup_disablecpui

cpumask_t cpu_initialized __cpuinitdata = CPU_MASK_NONE;

+static unsigned long long tsc_clock(int cpu)
+{
+ unsigned long long t;
+
+ rdtscll(t);
+
+ return t;
+}
+
void __init early_cpu_init(void)
{
struct cpu_vendor_dev *cvdev;
@@ -657,6 +666,8 @@ void __init early_cpu_init(void)
cpu_devs[cvdev->vendor] = cvdev->cpu_dev;

early_cpu_detect();
+ if (cpu_has_tsc)
+ set_printk_time_clock(tsc_clock);
validate_pat_support(&boot_cpu_data);
}

Index: linux-2.6/arch/x86/kernel/cpu/common_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/common_64.c
+++ linux-2.6/arch/x86/kernel/cpu/common_64.c
@@ -249,6 +249,15 @@ static void __cpuinit detect_nopl(struct
}
}

+static unsigned long long tsc_clock(int cpu)
+{
+ unsigned long long t;
+
+ rdtscll(t);
+
+ return t;
+}
+
static void __cpuinit early_identify_cpu(struct cpuinfo_x86 *c);

void __init early_cpu_init(void)
@@ -261,6 +270,9 @@ void __init early_cpu_init(void)
cpu_devs[cvdev->vendor] = cvdev->cpu_dev;
early_cpu_support_print();
early_identify_cpu(&boot_cpu_data);
+
+ if (cpu_has_tsc)
+ set_printk_time_clock(tsc_clock);
}

/* Do some early cpuid on the boot CPU to get some parameter that are