From patchwork Tue Jul 16 14:54:20 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yury Kotov X-Patchwork-Id: 11046217 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7D86413B1 for ; Tue, 16 Jul 2019 14:56:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6D26627F94 for ; Tue, 16 Jul 2019 14:56:46 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 616C62858A; Tue, 16 Jul 2019 14:56:46 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.0 required=2.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 0469B28585 for ; Tue, 16 Jul 2019 14:56:46 +0000 (UTC) Received: from localhost ([::1]:49798 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hnOsm-0005vg-WF for patchwork-qemu-devel@patchwork.kernel.org; Tue, 16 Jul 2019 10:56:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:50031) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hnOrE-0007kJ-7l for qemu-devel@nongnu.org; Tue, 16 Jul 2019 10:55:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hnOrB-0001M1-PN for qemu-devel@nongnu.org; Tue, 16 Jul 2019 10:55:07 -0400 Received: from forwardcorp1p.mail.yandex.net ([77.88.29.217]:54264) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hnOrA-0001Jl-Bw for qemu-devel@nongnu.org; Tue, 16 Jul 2019 10:55:05 -0400 Received: from mxbackcorp1j.mail.yandex.net (mxbackcorp1j.mail.yandex.net [IPv6:2a02:6b8:0:1619::162]) by forwardcorp1p.mail.yandex.net (Yandex) with ESMTP id A16312E1495; Tue, 16 Jul 2019 17:54:58 +0300 (MSK) Received: from smtpcorp1j.mail.yandex.net (smtpcorp1j.mail.yandex.net [2a02:6b8:0:1619::137]) by mxbackcorp1j.mail.yandex.net (nwsmtp/Yandex) with ESMTP id 8MGZrCVKIU-sw4Chkx7; Tue, 16 Jul 2019 17:54:58 +0300 Precedence: bulk DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1563288898; bh=JNDXgoKL65F2qbz8oiwPd7P/tXvktCtAirRQDC8fhvY=; h=In-Reply-To:Message-Id:References:Date:Subject:To:From:Cc; b=spexxzfEJYNqa068Xo1ZmmEdWjIuaivr3ogaayoTHti1MMHVzrwI5ldWRANR27sfl Rs3FkMYHaEhPYI7yF6c/HVKNBlxWv4l+PjXGeMGwHJepiGW8qMlpU4MWs8l81fMn1f 41e5sHSeUgAFxkd8Wi2n4ieSAS24GsaZ5HP70SuA= Authentication-Results: mxbackcorp1j.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-red.dhcp.yndx.net (dynamic-red.dhcp.yndx.net [2a02:6b8:0:40c:68fa:19fe:5639:24b5]) by smtpcorp1j.mail.yandex.net (nwsmtp/Yandex) with ESMTPSA id RzIFhwRP0o-svQip9CH; Tue, 16 Jul 2019 17:54:58 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (Client certificate not present) From: Yury Kotov To: Paolo Bonzini , Richard Henderson , Thomas Huth , Laurent Vivier , Juan Quintela , "Dr. David Alan Gilbert" , Stefan Weil Date: Tue, 16 Jul 2019 17:54:20 +0300 Message-Id: <20190716145421.17645-3-yury-kotov@yandex-team.ru> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190716145421.17645-1-yury-kotov@yandex-team.ru> References: <20190716145421.17645-1-yury-kotov@yandex-team.ru> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 77.88.29.217 Subject: [Qemu-devel] [PATCH v2 2/3] cpus: Fix throttling during vm_stop X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org, yc-core@yandex-team.ru Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Throttling thread sleeps in VCPU thread. For high throttle percentage this sleep is more than 10ms. E.g. for 60% - 15ms, for 99% - 990ms. vm_stop() kicks all VCPUs and waits for them. It's called at the end of migration and because of the long sleep the migration downtime might be more than 100ms even for downtime-limit 1ms. Use qemu_cond_timedwait for high percentage to wake up during vm_stop. Signed-off-by: Yury Kotov --- cpus.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/cpus.c b/cpus.c index ffc57119ca..c8817c9da7 100644 --- a/cpus.c +++ b/cpus.c @@ -74,6 +74,8 @@ #endif /* CONFIG_LINUX */ +static QemuMutex qemu_global_mutex; + int64_t max_delay; int64_t max_advance; @@ -776,7 +778,7 @@ static void cpu_throttle_thread(CPUState *cpu, run_on_cpu_data opaque) { double pct; double throttle_ratio; - long sleeptime_ns; + int64_t sleeptime_ns; if (!cpu_throttle_get_percentage()) { return; @@ -784,11 +786,22 @@ static void cpu_throttle_thread(CPUState *cpu, run_on_cpu_data opaque) 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(); - g_usleep(sleeptime_ns / 1000); /* Convert ns to us for usleep call */ - qemu_mutex_lock_iothread(); + /* Add 1ns to fix double's rounding error (like 0.9999999...) */ + sleeptime_ns = (int64_t)(throttle_ratio * CPU_THROTTLE_TIMESLICE_NS + 1); + + while (sleeptime_ns >= SCALE_MS && !cpu->stop) { + int64_t start, end; + start = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); + qemu_cond_timedwait(cpu->halt_cond, &qemu_global_mutex, + sleeptime_ns / SCALE_MS); + end = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); + sleeptime_ns -= end - start; + } + if (sleeptime_ns >= SCALE_US && !cpu->stop) { + qemu_mutex_unlock_iothread(); + g_usleep(sleeptime_ns / SCALE_US); + qemu_mutex_lock_iothread(); + } atomic_set(&cpu->throttle_thread_scheduled, 0); } @@ -1166,8 +1179,6 @@ static void qemu_init_sigbus(void) } #endif /* !CONFIG_LINUX */ -static QemuMutex qemu_global_mutex; - static QemuThread io_thread; /* cpu creation */