From patchwork Wed Sep 30 08:56:02 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Juan Quintela X-Patchwork-Id: 524746 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 1D18A140D68 for ; Thu, 1 Oct 2015 15:20:42 +1000 (AEST) Received: from localhost ([::1]:38134 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhWIJ-0002Uv-Uf for incoming@patchwork.ozlabs.org; Thu, 01 Oct 2015 01:20:39 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54068) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhDBP-0000PO-2z for qemu-devel@nongnu.org; Wed, 30 Sep 2015 04:56:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZhDBM-0001GL-Lv for qemu-devel@nongnu.org; Wed, 30 Sep 2015 04:56:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52727) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhDBM-0001G2-FN for qemu-devel@nongnu.org; Wed, 30 Sep 2015 04:56:12 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (Postfix) with ESMTPS id 21833C0B1B53; Wed, 30 Sep 2015 08:56:12 +0000 (UTC) Received: from trasno.mitica (ovpn-116-28.ams2.redhat.com [10.36.116.28]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t8U8u6AU030805; Wed, 30 Sep 2015 04:56:10 -0400 From: Juan Quintela To: qemu-devel@nongnu.org Date: Wed, 30 Sep 2015 10:56:02 +0200 Message-Id: <1443603366-4686-3-git-send-email-quintela@redhat.com> In-Reply-To: <1443603366-4686-1-git-send-email-quintela@redhat.com> References: <1443603366-4686-1-git-send-email-quintela@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: amit.shah@redhat.com, dgilbert@redhat.com, "Jason J. Herne" Subject: [Qemu-devel] [PULL 2/6] cpu: Provide vcpu throttling interface X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: "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 Signed-off-by: Juan Quintela Reviewed-by: Juan Quintela --- cpus.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ include/qom/cpu.h | 42 ++++++++++++++++++++++++++++++ 2 files changed, 120 insertions(+) diff --git a/cpus.c b/cpus.c index dddd056..d44c0ed 100644 --- a/cpus.c +++ b/cpus.c @@ -69,6 +69,14 @@ 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_NS 10000000 + bool cpu_is_stopped(CPUState *cpu) { return cpu->stopped || !runstate_is_running(); @@ -505,10 +513,80 @@ static const VMStateDescription vmstate_timers = { } }; +static void cpu_throttle_thread(void *opaque) +{ + CPUState *cpu = opaque; + double pct; + double throttle_ratio; + long sleeptime_ns; + + if (!cpu_throttle_get_percentage()) { + return; + } + + pct = (double)cpu_throttle_get_percentage()/100; + throttle_ratio = pct / (1 - pct); + sleeptime_ns = (long)(throttle_ratio * CPU_THROTTLE_TIMESLICE_NS); + + qemu_mutex_unlock_iothread(); + atomic_set(&cpu->throttle_thread_scheduled, 0); + g_usleep(sleeptime_ns / 1000); /* Convert ns 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_ns(QEMU_CLOCK_VIRTUAL_RT) + + CPU_THROTTLE_TIMESLICE_NS / (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_ns(QEMU_CLOCK_VIRTUAL_RT) + + CPU_THROTTLE_TIMESLICE_NS); +} + +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_ns(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 302673d..9405554 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -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);