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Violators will be prosecuted for from ; Tue, 1 Sep 2015 10:46:11 -0400 Received: from b01cxnp22036.gho.pok.ibm.com (b01cxnp22036.gho.pok.ibm.com [9.57.198.26]) by d01dlp01.pok.ibm.com (Postfix) with ESMTP id D75A238C8026 for ; Tue, 1 Sep 2015 10:46:07 -0400 (EDT) Received: from d01av05.pok.ibm.com (d01av05.pok.ibm.com [9.56.224.195]) by b01cxnp22036.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t81Ek7AI31326416 for ; Tue, 1 Sep 2015 14:46:07 GMT Received: from d01av05.pok.ibm.com (localhost [127.0.0.1]) by d01av05.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t81Ek4cB026791 for ; Tue, 1 Sep 2015 10:46:04 -0400 From: "Jason J. Herne" Date: Tue, 1 Sep 2015 10:45:59 -0400 Message-Id: <1441118763-17510-2-git-send-email-jjherne@linux.vnet.ibm.com> In-Reply-To: <1441118763-17510-1-git-send-email-jjherne@linux.vnet.ibm.com> References: <1441118763-17510-1-git-send-email-jjherne@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH v5 1/5] cpu: Provide vcpu throttling interface List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: afaerber@suse.de, amit.shah@redhat.com, dgilbert@redhat.com, borntraeger@de.ibm.com, quintela@redhat.com, qemu-devel@nongnu.org, pbonzini@redhat.com Cc: "Jason J. Herne" 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 Reviewed-by: Matthew Rosato --- cpus.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ include/qom/cpu.h | 43 ++++++++++++++++++++++++++++++ 2 files changed, 121 insertions(+) diff --git a/cpus.c b/cpus.c index de6469f..f504e72 100644 --- a/cpus.c +++ b/cpus.c @@ -68,6 +68,14 @@ static CPUState *next_cpu; int64_t max_delay; int64_t max_advance; +/* vcpu throttling controls */ +static QEMUTimer *throttle_timer; +static unsigned int throttle_percentage; + +#define CPU_THROTTLE_PCT_MIN 1 +#define CPU_THROTTLE_PCT_MAX 99 +#define CPU_THROTTLE_TIMESLICE 10 + bool cpu_is_stopped(CPUState *cpu) { return cpu->stopped || !runstate_is_running(); @@ -486,10 +494,80 @@ static const VMStateDescription vmstate_timers = { } }; +static void cpu_throttle_thread(void *opaque) +{ + CPUState *cpu = opaque; + double pct; + double throttle_ratio; + long sleeptime_ms; + + if (!cpu_throttle_get_percentage()) { + return; + } + + pct = (double)cpu_throttle_get_percentage()/100; + throttle_ratio = pct / (1 - pct); + sleeptime_ms = (long)(throttle_ratio * CPU_THROTTLE_TIMESLICE); + + qemu_mutex_unlock_iothread(); + atomic_set(&cpu->throttle_thread_scheduled, 0); + g_usleep(sleeptime_ms * 1000); /* Convert ms to us for usleep call */ + qemu_mutex_lock_iothread(); +} + +static void cpu_throttle_timer_tick(void *opaque) +{ + CPUState *cpu; + double pct; + + /* Stop the timer if needed */ + if (!cpu_throttle_get_percentage()) { + return; + } + CPU_FOREACH(cpu) { + if (!atomic_xchg(&cpu->throttle_thread_scheduled, 1)) { + async_run_on_cpu(cpu, cpu_throttle_thread, cpu); + } + } + + pct = (double)cpu_throttle_get_percentage()/100; + timer_mod(throttle_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) + + CPU_THROTTLE_TIMESLICE / (1-pct)); +} + +void cpu_throttle_set(int new_throttle_pct) +{ + /* Ensure throttle percentage is within valid range */ + new_throttle_pct = MIN(new_throttle_pct, CPU_THROTTLE_PCT_MAX); + new_throttle_pct = MAX(new_throttle_pct, CPU_THROTTLE_PCT_MIN); + + atomic_set(&throttle_percentage, new_throttle_pct); + + timer_mod(throttle_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) + + CPU_THROTTLE_TIMESLICE); +} + +void cpu_throttle_stop(void) +{ + atomic_set(&throttle_percentage, 0); +} + +bool cpu_throttle_active(void) +{ + return (cpu_throttle_get_percentage() != 0); +} + +int cpu_throttle_get_percentage(void) +{ + return atomic_read(&throttle_percentage); +} + void cpu_ticks_init(void) { seqlock_init(&timers_state.vm_clock_seqlock, NULL); vmstate_register(NULL, 0, &vmstate_timers, &timers_state); + throttle_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL_RT, + cpu_throttle_timer_tick, NULL); } void configure_icount(QemuOpts *opts, Error **errp) diff --git a/include/qom/cpu.h b/include/qom/cpu.h index 39f0f19..fdca10c 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -310,6 +310,11 @@ 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 @@ -553,6 +558,44 @@ CPUState *qemu_get_cpu(int index); */ bool cpu_exists(int64_t id); +/** + * cpu_throttle_set: + * @new_throttle_pct: Percent of sleep time to running 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 50 corresponds to a 50% duty cycle roughly. + * (example: 10ms sleep for every 10ms 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); -- 1.9.1