Commit b0c3cf94 authored by Claudio Fontana's avatar Claudio Fontana Committed by Paolo Bonzini
Browse files

cpu-throttle: new module, extracted from cpus.c 



move the vcpu throttling functionality into its own module.

This functionality is not specific to any accelerator,
and it is used currently by migration to slow down guests to try to
have migrations converge, and by the cocoa MacOS UI to throttle speed.

cpu-throttle contains the controls to adjust and inspect throttle
settings, start (set) and stop vcpu throttling, and the throttling
function itself that is run periodically on vcpus to make them take a nap.

Execution of the throttling function on all vcpus is triggered by a timer,
registered at module initialization.

No functionality change.

Signed-off-by: default avatarClaudio Fontana <cfontana@suse.de>
Reviewed-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: default avatarLaurent Vivier <lvivier@redhat.com>
Message-Id: <20200629093504.3228-3-cfontana@suse.de>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c7f419f5

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -2247,6 +2247,7 @@ F: util/qemu-timer.c 
F: softmmu/vl.c

F: softmmu/main.c

F: softmmu/cpus.c

F: softmmu/cpu-throttle.c

F: qapi/run-state.json



Human Monitor (HMP)

include/hw/core/cpu.h

+0 −37
Original line number Diff line number Diff line
@@ -822,43 +822,6 @@ bool cpu_exists(int64_t id); 
 */

CPUState *cpu_by_arch_id(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);

include/qemu/main-loop.h

+5 −0
Original line number Diff line number Diff line
@@ -303,6 +303,11 @@ void qemu_mutex_unlock_iothread(void); 
 */

void qemu_cond_wait_iothread(QemuCond *cond);



/*

 * qemu_cond_timedwait_iothread: like the previous, but with timeout

 */

void qemu_cond_timedwait_iothread(QemuCond *cond, int ms);



/* internal interfaces */



void qemu_fd_register(int fd);

include/sysemu/cpu-throttle.h

0 → 100644
+68 −0
Original line number Diff line number Diff line 
/*

 * Copyright (c) 2012 SUSE LINUX Products GmbH

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, see

 * <http://www.gnu.org/licenses/gpl-2.0.html>

 */



#ifndef SYSEMU_CPU_THROTTLE_H

#define SYSEMU_CPU_THROTTLE_H



#include "qemu/timer.h"



/**

 * cpu_throttle_init:

 *

 * Initialize the CPU throttling API.

 */

void cpu_throttle_init(void);



/**

 * 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);



#endif /* SYSEMU_CPU_THROTTLE_H */

migration/migration.c

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include "socket.h"

#include "sysemu/runstate.h"

#include "sysemu/sysemu.h"

#include "sysemu/cpu-throttle.h"

#include "rdma.h"

#include "ram.h"

#include "migration/global_state.h"