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cpu: Provide vcpu throttling interface

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Provide a method to throttle guest cpu execution. CPUState is augmented with
timeout controls and throttle start/stop functions. To throttle the guest cpu
the caller simply has to call the throttle set function and provide a percentage
of throttle time.

Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Jason J. Herne 2015-09-08 13:12:33 -04:00 • committed by Juan Quintela
parent 2a6e6e59df
commit 2adcc85d40
2 changed files with 120 additions and 0 deletions
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42
include/qom/cpu.h
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@ -321,6 +321,11 @@ struct CPUState {
uint32_t can_do_io;
int32_t exception_index; /* used by m68k TCG */
/* Used to keep track of an outstanding cpu throttle thread for migration
* autoconverge
*/
bool throttle_thread_scheduled;
/* Note that this is accessed at the start of every TB via a negative
offset from AREG0. Leave this field at the end so as to make the
(absolute value) offset as small as possible. This reduces code
@ -565,6 +570,43 @@ CPUState *qemu_get_cpu(int index);
*/
bool cpu_exists(int64_t id);
/**
* cpu_throttle_set:
* @new_throttle_pct: Percent of sleep time. Valid range is 1 to 99.
*
* Throttles all vcpus by forcing them to sleep for the given percentage of
* time. A throttle_percentage of 25 corresponds to a 75% duty cycle roughly.
* (example: 10ms sleep for every 30ms awake).
*
* cpu_throttle_set can be called as needed to adjust new_throttle_pct.
* Once the throttling starts, it will remain in effect until cpu_throttle_stop
* is called.
*/
void cpu_throttle_set(int new_throttle_pct);
/**
* cpu_throttle_stop:
*
* Stops the vcpu throttling started by cpu_throttle_set.
*/
void cpu_throttle_stop(void);
/**
* cpu_throttle_active:
*
* Returns: %true if the vcpus are currently being throttled, %false otherwise.
*/
bool cpu_throttle_active(void);
/**
* cpu_throttle_get_percentage:
*
* Returns the vcpu throttle percentage. See cpu_throttle_set for details.
*
* Returns: The throttle percentage in range 1 to 99.
*/
int cpu_throttle_get_percentage(void);
#ifndef CONFIG_USER_ONLY
typedef void (*CPUInterruptHandler)(CPUState *, int);