Timestamp Counter

Collaboration diagram for Timestamp Counter:

Files
file	rdtsc.h
	Timestamp counter related functions.
file	rdtsc.h
	Timestamp counter related functions.

Functions
l4_cpu_time_t	l4_rdtsc (void)
	Read current value of CPU-internal timestamp counter.
l4_uint32_t	l4_rdtsc_32 (void)
	Read the lest significant 32 bit of the TSC.
l4_uint64_t	l4_rdpmc (int ecx)
	Return current value of CPU-internal performance measurement counter.
l4_uint32_t	l4_rdpmc_32 (int ecx)
	Return the least significant 32 bit of a performance counter.
l4_uint64_t	l4_tsc_to_ns (l4_cpu_time_t tsc)
	Convert timestamp to ns value.
l4_uint64_t	l4_tsc_to_us (l4_cpu_time_t tsc)
	Convert timestamp into micro seconds value.
void	l4_tsc_to_s_and_ns (l4_cpu_time_t tsc, l4_uint32_t *s, l4_uint32_t *ns)
	Convert timestamp to s.ns value.
l4_cpu_time_t	l4_ns_to_tsc (l4_uint64_t ns)
	Convert nano seconds into CPU ticks.
void	l4_busy_wait_ns (l4_uint64_t ns)
	Wait busy for a small amount of time.
void	l4_busy_wait_us (l4_uint64_t us)
	Wait busy for a small amount of time.
l4_uint32_t	l4_calibrate_tsc (l4_kernel_info_t const *kip)
	Determine scalers for timestamp calculations.
l4_uint32_t	l4_tsc_init (l4_kernel_info_t const *kip)
	Initialize scaler for TSC calibrations from the kernel.
l4_uint32_t	l4_get_hz (void)
	Get CPU frequency in Hz.

Detailed Description

Function Documentation

l4_busy_wait_ns()

void l4_busy_wait_ns ( l4_uint64_t  ns )

inline

Wait busy for a small amount of time.

Parameters

ns	nano seconds to wait

Attention

Not intended for any use!

Definition at line 264 of file rdtsc.h.

References l4_ns_to_tsc(), and l4_rdtsc().

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l4_busy_wait_us()

void l4_busy_wait_us ( l4_uint64_t  us )

inline

Wait busy for a small amount of time.

Parameters

us	micro seconds to wait

Attention

Not intended for any use!

Definition at line 274 of file rdtsc.h.

References l4_ns_to_tsc(), and l4_rdtsc().

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l4_calibrate_tsc()

l4_uint32_t l4_calibrate_tsc ( l4_kernel_info_t const *  kip )

inline

Determine scalers for timestamp calculations.

Determine some scalers to be able to convert between real time and CPU ticks. Just calls l4_tsc_init().

Examples

examples/sys/aliens/main.c.

Definition at line 161 of file rdtsc.h.

References l4_tsc_init().

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l4_get_hz()

l4_uint32_t l4_get_hz

(

void

)

Get CPU frequency in Hz.

Returns

frequency in Hz

l4_ns_to_tsc()

l4_cpu_time_t l4_ns_to_tsc ( l4_uint64_t  ns )

inline

Convert nano seconds into CPU ticks.

Parameters

ns	nano seconds

Returns

CPU ticks

Definition at line 250 of file rdtsc.h.

Referenced by l4_busy_wait_ns(), and l4_busy_wait_us().

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l4_rdpmc()

l4_uint64_t l4_rdpmc ( int  ecx )

inline

Return current value of CPU-internal performance measurement counter.

Parameters

ecx	ECX value for the rdpmc instruction. For details see the Intel IA-32 Architectures Software Developer's Manual.

Returns

64-bit PMC

Definition at line 177 of file rdtsc.h.

l4_rdpmc_32()

l4_uint32_t l4_rdpmc_32 ( int  ecx )

inline

Return the least significant 32 bit of a performance counter.

Useful for smaller differences, needs less cycles.

Definition at line 197 of file rdtsc.h.

l4_rdtsc()

l4_cpu_time_t l4_rdtsc ( void  )

inline

Read current value of CPU-internal timestamp counter.

Returns

64-bit timestamp

Examples

examples/sys/aliens/main.c.

Definition at line 167 of file rdtsc.h.

Referenced by l4_busy_wait_ns(), and l4_busy_wait_us().

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l4_rdtsc_32()

l4_uint32_t l4_rdtsc_32 ( void  )

inline

Read the lest significant 32 bit of the TSC.

Useful for smaller differences, needs less cycles.

Definition at line 187 of file rdtsc.h.

l4_tsc_init()

l4_uint32_t l4_tsc_init

(

l4_kernel_info_t const *

kip

)

Initialize scaler for TSC calibrations from the kernel.

Initialize the scalers needed by l4_tsc_to_ns()/l4_ns_to_tsc() and so on. Use the kernel-provided frequency.

Parameters

kip	KIP pointer

Returns

0 on error (no scalers exported by kernel) otherwise returns (2^32 / (tsc per µsec)). This value has the same semantics as the value returned by the calibrate_delay_loop() function of the Linux kernel.

Referenced by l4_calibrate_tsc().

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l4_tsc_to_ns()

l4_uint64_t l4_tsc_to_ns ( l4_cpu_time_t  tsc )

inline

Convert timestamp to ns value.

Parameters

tsc	time value in CPU ticks

Returns

time value in ns

Examples

examples/sys/aliens/main.c.

Definition at line 207 of file rdtsc.h.

l4_tsc_to_s_and_ns()

void l4_tsc_to_s_and_ns ( l4_cpu_time_t  tsc, l4_uint32_t *  s, l4_uint32_t *  ns  )

inline

Convert timestamp to s.ns value.

Parameters

	tsc	time value in CPU ticks
[out]	s	seconds
[out]	ns	nano seconds

Definition at line 235 of file rdtsc.h.

l4_tsc_to_us()

l4_uint64_t l4_tsc_to_us ( l4_cpu_time_t  tsc )

inline

Convert timestamp into micro seconds value.

Parameters

tsc	time value in CPU ticks

Returns

time value in micro seconds

Definition at line 221 of file rdtsc.h.