PerfEvent based timer using the host's CPU cycle counter. More...
#include <timer.hh>
Public Member Functions | |
| PerfKvmTimer (PerfKvmCounter &ctr, int signo, float hostFactor, Tick hostFreq) | |
| Create a timer that uses an existing hardware cycle counter. More... | |
| ~PerfKvmTimer () | |
| void | arm (Tick ticks) |
| Arm the timer so that it fires after a certain number of ticks. More... | |
| void | disarm () |
| Disarm the timer. More... | |
 Public Member Functions inherited from BaseKvmTimer | |
| BaseKvmTimer (int signo, float hostFactor, Tick hostFreq) | |
| Setup basic timer functionality shared by all timer implementations. More... | |
| virtual | ~BaseKvmTimer () |
| virtual bool | expired () |
| Tick | resolution () |
| Determine the resolution of the timer in ticks. More... | |
| Tick | ticksFromHostCycles (uint64_t cycles) |
| Convert cycles executed on the host into Ticks executed in the simulator. More... | |
| Tick | ticksFromHostNs (uint64_t ns) |
| Convert nanoseconds executed on the host into Ticks executed in the simulator. More... | |
Protected Member Functions | |
| Tick | calcResolution () |
| Calculate the timer resolution, used by resolution() which caches the result. More... | |
| Protected Member Functions inherited from BaseKvmTimer | |
| uint64_t | hostNs (Tick ticks) |
| Convert a time in simulator ticks to host nanoseconds. More... | |
| uint64_t | hostCycles (Tick ticks) |
| Convert a time in simulator ticks to host cycles. More... | |
Private Attributes | |
| PerfKvmCounter & | hwOverflow |
Additional Inherited Members | |
| Protected Attributes inherited from BaseKvmTimer | |
| int | signo |
| Signal to deliver when the timer times out. More... | |
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.
Constructor & Destructor Documentation
◆ PerfKvmTimer()
| 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 168 of file timer.cc.
References PerfKvmCounter::enableSignals(), hwOverflow, and BaseKvmTimer::signo.
◆ ~PerfKvmTimer()
Member Function Documentation
◆ arm()
|
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
Implements BaseKvmTimer.
Definition at line 181 of file timer.cc.
References BaseKvmTimer::hostCycles(), hwOverflow, PerfKvmCounter::period(), and PerfKvmCounter::refresh().
◆ calcResolution()
|
protectedvirtual |
Calculate the timer resolution, used by resolution() which caches the result.
- Returns
- Minimum number of ticks the timer can resolve
Implements BaseKvmTimer.
Definition at line 194 of file timer.cc.
References MIN_HOST_CYCLES, and BaseKvmTimer::ticksFromHostCycles().
◆ disarm()
|
virtual |
Disarm the timer.
When this method has returned, the timer may no longer deliver signals upon timeout.
Implements BaseKvmTimer.
Definition at line 188 of file timer.cc.
References hwOverflow, and PerfKvmCounter::stop().
Member Data Documentation
◆ hwOverflow
|
private |
Definition at line 247 of file timer.hh.
Referenced by arm(), disarm(), and PerfKvmTimer().
The documentation for this class was generated from the following files: