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printk_time: prepare stub for using other than cpu_clock

PATCH New Yinghai Lu 2 participants 4 messages Jul 29, 2008 x86

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Yinghai Lu

author
#0 lore raw

PATCH 1/1 printk_time: prepare stub for using other than cpu_clock

Signed-off-by Yinghai Lu <[email protected]>
---
 include/linux/kernel.h |    5 +++++
 init/main.c            |    1 +
 kernel/printk.c        |   14 +++++++++++++-
 3 files changed, 19 insertions(+), 1 deletion(-)
include/linux/kernel.h +5 -0
Index: linux-2.6/include/linux/kernel.h
===================================================================
@@ -184,7 +184,10 @@ extern int kernel_text_address(unsigned
 struct pid;
 extern struct pid *session_of_pgrp(struct pid *pgrp);
 
+typedef unsigned long long (*printk_time_clock_fn)(int cpu);
 #ifdef CONFIG_PRINTK
+extern void set_printk_time_clock(printk_time_clock_fn fn);
+
 asmlinkage int vprintk(const char *fmt, va_list args)
 	__attribute__ ((format (printf, 1, 0)));
 asmlinkage int printk(const char * fmt, ...)

@@ -195,6 +198,8 @@ extern int printk_ratelimit(void);
 extern bool printk_timed_ratelimit(unsigned long *caller_jiffies,
 				   unsigned int interval_msec);
 #else
+static inline void set_printk_time_clock(printk_time_clock_fn fn) { }
+
 static inline int vprintk(const char *s, va_list args)
 	__attribute__ ((format (printf, 1, 0)));
 static inline int vprintk(const char *s, va_list args) { return 0; }
init/main.c +1 -0
Index: linux-2.6/init/main.c
===================================================================
@@ -663,6 +663,7 @@ asmlinkage void __init start_kernel(void
 	if (late_time_init)
 		late_time_init();
 	calibrate_delay();
+	set_printk_time_clock(cpu_clock);
 	pidmap_init();
 	pgtable_cache_init();
 	prio_tree_init();
kernel/printk.c +13 -1
Index: linux-2.6/kernel/printk.c
===================================================================
@@ -662,6 +662,18 @@ static int recursion_bug;
 	static int new_text_line = 1;
 static char printk_buf[1024];
 
+static unsigned long long default_printk_time_clock(int cpu)
+{
+	return 0;
+}
+
+static printk_time_clock_fn printk_time_clock = default_printk_time_clock;
+
+void set_printk_time_clock(printk_time_clock_fn fn)
+{
+	printk_time_clock = fn;
+}
+
 asmlinkage int vprintk(const char *fmt, va_list args)
 {
 	int printed_len = 0;

@@ -737,7 +749,7 @@ asmlinkage int vprintk(const char *fmt,
 				unsigned long long t;
 				unsigned long nanosec_rem;
 
-				t = cpu_clock(printk_cpu);
+				t = printk_time_clock(printk_cpu);
 				nanosec_rem = do_div(t, 1000000000);
 				tlen = sprintf(tbuf, "[%5lu.%06lu] ",
 						(unsigned long) t,
author
#1 lore raw

PATCH 1/1 x86: printk_time to use tsc before cpu_clock is ready

so can get tsc value on printk

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

Signed-off-by Yinghai Lu <[email protected]>
---
 arch/x86/kernel/cpu/common.c    |   11 +++++++++++
 arch/x86/kernel/cpu/common_64.c |   12 ++++++++++++
 2 files changed, 23 insertions(+)
arch/x86/kernel/cpu/common.c +11 -0
Index: linux-2.6/arch/x86/kernel/cpu/common.c
===================================================================
@@ -617,6 +617,15 @@ __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;

@@ -627,6 +636,8 @@ 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);
 }
arch/x86/kernel/cpu/common_64.c +12 -0
Index: linux-2.6/arch/x86/kernel/cpu/common_64.c
===================================================================
@@ -215,6 +215,15 @@ static void __init early_cpu_support_pri
 	}
 }
 
+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)

@@ -227,6 +236,9 @@ 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
#2 lore raw

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

Quoted 4 lines · Yinghai Lu

so can get tsc value on printk

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

You failed to mention why we want this... ;-)

Quoted 71 lines
Signed-off-by Yinghai Lu <[email protected]>
---
 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
===================================================================

arch/x86/kernel/cpu/common.c +11 -0
@@ -617,6 +617,15 @@ __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;

@@ -627,6 +636,8 @@ 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
===================================================================

arch/x86/kernel/cpu/common_64.c +12 -1
@@ -215,6 +215,15 @@ static void __init early_cpu_support_pri
 	}
 }
 
+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)

@@ -227,6 +236,9 @@ 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
--

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author
#3 lore raw

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

Quoted 9 lines · Peter Zijlstra
Quoted 4 lines · Yinghai Lu

so can get tsc value on printk

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

You failed to mention why we want this... ;-)

"
otherwise will get

[    0.000000]....
.....
[    0.000000] TSC calibrated against PM_TIMER
[    0.000000] Detected 2493.378 MHz processor.
[    0.008000] spurious 8259A interrupt: IRQ7.
[    0.008000] Console: colour VGA+ 80x25
[    0.008000] console handover: boot [uart0] -> real [ttyS0]
[    0.008000] Checking aperture...
[    0.008000] No AGP bridge found
[    0.008000] Node 0: aperture @ dc000000 size 64 MB
[    0.008000] Node 1: aperture @ dc000000 size 64 MB
[    0.008000] Node 2: aperture @ dc000000 size 64 MB
[    0.008000] Node 3: aperture @ dc000000 size 64 MB
[    0.008000] Node 4: aperture @ dc000000 size 64 MB
[    0.008000] Node 5: aperture @ dc000000 size 64 MB
[    0.008000] Node 6: aperture @ dc000000 size 64 MB
[    0.008000] Node 7: aperture @ dc000000 size 64 MB
[    0.008000] Memory: 264718324k/269090816k available (7532k kernel
code, 3716316k reserved, 5099k data, 484k init)
[    0.008000] CPA: page pool initialized 1 of 1 pages preallocated
[    0.008000] SLUB: Genslabs=13, HWalign=64, Order=0-3, MinObjects=0,
CPUs=32, Nodes=8
[    0.008000] hpet clockevent registered
[    0.008000] Calibrating delay loop (skipped), value calculated
using timer frequency.. 4986.72 BogoMIPS (lpj=9973456)
[    0.060003] Dentry cache hash table entries: 33554432 (order: 16,

268435456 bytes)

with this patch could get tsc to replace those [0,000000] and

[0.0080000], so could debug possible delay on big system on early

stage.
"

YH