PerfEvent based timer using the host's CPU cycle counter. More...

#include <timer.hh>

Inheritance diagram for gem5::PerfKvmTimer:

Public Member Functions
	PerfKvmTimer (PerfKvmCounter &ctr, int signo, float hostFactor, Tick hostFreq)
	Create a timer that uses an existing hardware cycle counter.

	~PerfKvmTimer ()

void	arm (Tick ticks)
	Arm the timer so that it fires after a certain number of ticks.

void	disarm ()
	Disarm the timer.

Public Member Functions inherited from gem5::BaseKvmTimer
	BaseKvmTimer (int signo, float hostFactor, Tick hostFreq)
	Setup basic timer functionality shared by all timer implementations.

virtual	~BaseKvmTimer ()

virtual bool	expired ()

Tick	resolution ()
	Determine the resolution of the timer in ticks.

Tick	ticksFromHostCycles (uint64_t cycles)
	Convert cycles executed on the host into Ticks executed in the simulator.

Tick	ticksFromHostNs (uint64_t ns)
	Convert nanoseconds executed on the host into Ticks executed in the simulator.

Protected Member Functions
Tick	calcResolution ()
	Calculate the timer resolution, used by resolution() which caches the result.

Protected Member Functions inherited from gem5::BaseKvmTimer
uint64_t	hostNs (Tick ticks)
	Convert a time in simulator ticks to host nanoseconds.

uint64_t	hostCycles (Tick ticks)
	Convert a time in simulator ticks to host cycles.

Additional Inherited Members
Protected Attributes inherited from gem5::BaseKvmTimer
int	signo
	Signal to deliver when the timer times out.

Detailed Description

PerfEvent based timer using the host's CPU cycle counter.

Warning: There is a known problem in some versions of the PerfEvent API that prevents the counter overflow period from being updated reliably, which might break this timer. See PerfKvmCounter::period() for details.

Definition at line 221 of file timer.hh.

Constructor & Destructor Documentation

gem5::PerfKvmTimer::PerfKvmTimer	(	PerfKvmCounter &	ctr,
		int	signo,
		float	hostFactor,
		Tick	hostFreq )

Create a timer that uses an existing hardware cycle counter.

Note: The performance counter must be configured for overflow sampling, which in practice means that it must have a non-zero sample period. The initial sample period is ignored since period will be updated when arm() is called.

Parameters

ctr	Attached performance counter configured for overflow reporting.
signo	Signal to deliver
hostFactor	Performance scaling factor
hostFreq	Clock frequency of the host

Definition at line 171 of file timer.cc.

gem5::PerfKvmTimer::~PerfKvmTimer ( )

Definition at line 179 of file timer.cc.

void gem5::PerfKvmTimer::arm ( Tick ticks )

virtual

Arm the timer so that it fires after a certain number of ticks.

Note: A timer implementation is free to convert between simulation ticks and virtualized time using any method it chooses. The accuracy of the timer therefore depends on what it measures, an accurate timer implementation should measure the number of cycles or instructions executed in the guest. If such counters are unavailable, it may fallback to wall clock time.

Parameters

ticks Number of ticks until the timer fires

Definition at line 184 of file timer.cc.