From patchwork Mon Sep 9 13:13:34 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yury Kotov X-Patchwork-Id: 11137931 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9380D17E6 for ; Mon, 9 Sep 2019 13:15:24 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6A6922086D for ; Mon, 9 Sep 2019 13:15:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="1cu+3DFh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6A6922086D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:56506 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i7JVq-0005Rv-CQ for patchwork-qemu-devel@patchwork.kernel.org; Mon, 09 Sep 2019 09:15:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56987) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i7JUP-0004Dk-GQ for qemu-devel@nongnu.org; Mon, 09 Sep 2019 09:13:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i7JUO-0002ag-8F for qemu-devel@nongnu.org; Mon, 09 Sep 2019 09:13:53 -0400 Received: from forwardcorp1j.mail.yandex.net ([2a02:6b8:0:1619::183]:46168) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i7JUN-0002Yw-UL for qemu-devel@nongnu.org; Mon, 09 Sep 2019 09:13:52 -0400 Received: from mxbackcorp1g.mail.yandex.net (mxbackcorp1g.mail.yandex.net [IPv6:2a02:6b8:0:1402::301]) by forwardcorp1j.mail.yandex.net (Yandex) with ESMTP id BEFE52E1481; Mon, 9 Sep 2019 16:13:47 +0300 (MSK) Received: from smtpcorp1j.mail.yandex.net (smtpcorp1j.mail.yandex.net [2a02:6b8:0:1619::137]) by mxbackcorp1g.mail.yandex.net (nwsmtp/Yandex) with ESMTP id 81RcB9CVoZ-DhCuu20S; Mon, 09 Sep 2019 16:13:47 +0300 Precedence: bulk DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1568034827; bh=SDYDVXTpeI0Jj9mPg05YC4j/rBpohEZTKIE7+3MKUQI=; h=In-Reply-To:Message-Id:References:Date:Subject:To:From:Cc; b=1cu+3DFhOWbfXjwAq1fhvouOBOIR1oWylTlQVXc8VtFMjj/TSGPVkhizwxaqF4zWM rTiHJENhir3KbD5sOGK78EFIcNgYABWHPiYXYCqw9522rpLykXW2bN40bv2SDavGHM PxvI8rMsnlqAT7dpAHmufLj9ni4ZjA4FWpT0seIk= Authentication-Results: mxbackcorp1g.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-red.dhcp.yndx.net (dynamic-red.dhcp.yndx.net [2a02:6b8:0:408:c41:6db7:e9d4:e9e0]) by smtpcorp1j.mail.yandex.net (nwsmtp/Yandex) with ESMTPSA id epZFdTz6L0-Dh7CYkbB; Mon, 09 Sep 2019 16:13:43 +0300 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (Client certificate not present) From: Yury Kotov To: "Dr. David Alan Gilbert" , Eric Blake , Juan Quintela , Laurent Vivier , Paolo Bonzini , Richard Henderson , Stefan Weil , Thomas Huth Date: Mon, 9 Sep 2019 16:13:34 +0300 Message-Id: <20190909131335.16848-3-yury-kotov@yandex-team.ru> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190909131335.16848-1-yury-kotov@yandex-team.ru> References: <20190909131335.16848-1-yury-kotov@yandex-team.ru> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2a02:6b8:0:1619::183 Subject: [Qemu-devel] [PATCH v7 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" 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 Reviewed-by: Eric Blake --- cpus.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/cpus.c b/cpus.c index 85cd451a86..d2c61ff155 100644 --- a/cpus.c +++ b/cpus.c @@ -77,6 +77,8 @@ #endif /* CONFIG_LINUX */ +static QemuMutex qemu_global_mutex; + int64_t max_delay; int64_t max_advance; @@ -782,7 +784,7 @@ static void cpu_throttle_thread(CPUState *cpu, run_on_cpu_data opaque) { double pct; double throttle_ratio; - long sleeptime_ns; + int64_t sleeptime_ns, endtime_ns; if (!cpu_throttle_get_percentage()) { return; @@ -790,11 +792,20 @@ 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); + endtime_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + sleeptime_ns; + while (sleeptime_ns > 0 && !cpu->stop) { + if (sleeptime_ns > SCALE_MS) { + qemu_cond_timedwait(cpu->halt_cond, &qemu_global_mutex, + sleeptime_ns / SCALE_MS); + } else { + qemu_mutex_unlock_iothread(); + g_usleep(sleeptime_ns / SCALE_US); + qemu_mutex_lock_iothread(); + } + sleeptime_ns = endtime_ns - qemu_clock_get_ns(QEMU_CLOCK_REALTIME); + } atomic_set(&cpu->throttle_thread_scheduled, 0); } @@ -1172,8 +1183,6 @@ static void qemu_init_sigbus(void) } #endif /* !CONFIG_LINUX */ -static QemuMutex qemu_global_mutex; - static QemuThread io_thread; /* cpu creation */