From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1652DC76191 for ; Mon, 15 Jul 2019 12:54:52 +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 E6FC72080A for ; Mon, 15 Jul 2019 12:54:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E6FC72080A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38234 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hn0VH-0005sO-8C for qemu-devel@archiver.kernel.org; Mon, 15 Jul 2019 08:54:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40832) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hn0V6-0005RZ-OK for qemu-devel@nongnu.org; Mon, 15 Jul 2019 08:54:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hn0V5-0003qO-S5 for qemu-devel@nongnu.org; Mon, 15 Jul 2019 08:54:40 -0400 Received: from mail-wm1-f66.google.com ([209.85.128.66]:37993) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1hn0V5-0003q5-LZ for qemu-devel@nongnu.org; Mon, 15 Jul 2019 08:54:39 -0400 Received: by mail-wm1-f66.google.com with SMTP id s15so15105159wmj.3 for ; Mon, 15 Jul 2019 05:54:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=ukoAT6+gEKpMBwrhcoJ9BUgWWljRFqQvpVWh1j9reGA=; b=Ek42vXcMGN7y22lUEf23FkReDgrHHkgQI9FaeM3RxxvHqynRZL1XmXdBjS1I3tlVWF cqDvbXWHWw/uUzXNmhWPSVElVFV+C2KchQhSNZdIoTbgkn7mqj9QpWRn5pchtdpQ6xMU O/7On8cp7Po4bp8/uTB60s991rJZfYZE4B2kefK+7moE8pez68cBPdx0UDCqCF8kxMA0 twP5MXrE+FPwDZwoPs3sZBaRH3qcgAUJvsNJ1C3RuYQgglqSqN7cdwt5swhQp0TKZR+3 ULWWXgTdZ8RthcgLD3XCO/IpPFgdd1ZIBSjFbI1wrbOFx6zXB4fll0LnyuDQZhRVgq/v 1X4Q== X-Gm-Message-State: APjAAAWrp6gGchOQG4IiURFh77CvBs5yc0o4dnOg3p+ilzs50GucbtMP rw1Drf0vg816XGSofLScKVoCiA== X-Google-Smtp-Source: APXvYqzt258txbv3xo4lvmO0n7sp/EXIZKfoMUAWLileo3VhVqgyMnAqFfzFbcyl2PK9N1AnzIsJUw== X-Received: by 2002:a1c:a019:: with SMTP id j25mr22286919wme.95.1563195278465; Mon, 15 Jul 2019 05:54:38 -0700 (PDT) Received: from [192.168.178.40] ([151.20.129.151]) by smtp.gmail.com with ESMTPSA id t24sm16047573wmj.14.2019.07.15.05.54.37 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 15 Jul 2019 05:54:37 -0700 (PDT) To: Yury Kotov , Richard Henderson References: <20190710092338.23559-1-yury-kotov@yandex-team.ru> <20190710092338.23559-3-yury-kotov@yandex-team.ru> <1262801563183599@vla1-1374b6242101.qloud-c.yandex.net> <50b64ede-13c1-6887-aaef-75ced63aaeda@redhat.com> <1198471563194184@iva8-147456c4bd40.qloud-c.yandex.net> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Mon, 15 Jul 2019 14:54:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <1198471563194184@iva8-147456c4bd40.qloud-c.yandex.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.128.66 Subject: Re: [Qemu-devel] [RFC PATCH 2/2] cpus: Fix throttling during vm_stop X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Stefan Weil , "Dr. David Alan Gilbert" , "open list:Overall" , "yc-core@yandex-team.ru" , Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 15/07/19 14:36, Yury Kotov wrote: > Sorry, perhaps I was not accurate enough. > > To fix the bug I changed the logic of cpu_throttle_thread() function. > Before this function called qemu_mutex_(un)lock_iothread which encapsulates > work with qemu_global_mutex. > > Now, this calls qemu_cond_timedwait(..., &qemu_global_mutex, ...) which also > unlocks/locks qemu_global_mutex. But, in theory, behavior of > qemu_mutex_(un)lock_iothread may differ from simple locking/unlocking of > qemu_global_mutex. > > So, I'm not sure is such change is ok or not. Ah, I see. No, it's okay. The only difference is setting/clearing iothread_locked which doesn't matter here. Paolo