From nobody Wed Nov 5 19:07:36 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1496333186623740.95598180762; Thu, 1 Jun 2017 09:06:26 -0700 (PDT) Received: from localhost ([::1]:45559 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dGScB-00016K-3y for importer@patchew.org; Thu, 01 Jun 2017 12:06:23 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39526) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dGSZq-0007i3-K7 for qemu-devel@nongnu.org; Thu, 01 Jun 2017 12:03:59 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dGSZp-00007i-BO for qemu-devel@nongnu.org; Thu, 01 Jun 2017 12:03:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49148) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dGSZp-000072-5Y for qemu-devel@nongnu.org; Thu, 01 Jun 2017 12:03:57 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 152E019C622; Thu, 1 Jun 2017 16:03:56 +0000 (UTC) Received: from donizetti.redhat.com (ovpn-117-20.ams2.redhat.com [10.36.117.20]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v51G3oKw013334; Thu, 1 Jun 2017 12:03:54 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 152E019C622 Authentication-Results: ext-mx09.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx09.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=pbonzini@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 152E019C622 From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Thu, 1 Jun 2017 18:03:50 +0200 Message-Id: <20170601160350.10767-3-pbonzini@redhat.com> In-Reply-To: <20170601160350.10767-1-pbonzini@redhat.com> References: <20170601160350.10767-1-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Thu, 01 Jun 2017 16:03:56 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 34/34] cpus: reset throttle_thread_scheduled after sleep X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Malcolm Crossley , Felipe Franciosi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Felipe Franciosi Currently, the throttle_thread_scheduled flag is reset back to 0 before sleeping (as part of the throttling logic). Given that throttle_timer (well, any timer) may tick with a slight delay, it so happens that under heavy throttling (ie. close or on CPU_THROTTLE_PCT_MAX) the tick may schedule a further cpu_throttle_thread() work item after the flag reset, but before the previous sleep completed. This results on the vCPU thread sleeping continuously for potentially several seconds in a row. The chances of that happening can be drastically minimised by resetting the flag after the sleep. Signed-off-by: Felipe Franciosi Signed-off-by: Malcolm Crossley Message-Id: <1495229390-18909-1-git-send-email-felipe@nutanix.com> Acked-by: Jason J. Herne Signed-off-by: Paolo Bonzini --- cpus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/cpus.c b/cpus.c index 516e5cbac1..f42eebda91 100644 --- a/cpus.c +++ b/cpus.c @@ -677,9 +677,9 @@ static void cpu_throttle_thread(CPUState *cpu, run_on_c= pu_data opaque) sleeptime_ns =3D (long)(throttle_ratio * CPU_THROTTLE_TIMESLICE_NS); =20 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(); + atomic_set(&cpu->throttle_thread_scheduled, 0); } =20 static void cpu_throttle_timer_tick(void *opaque) --=20 2.13.0