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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 30A7AC433ED for ; Mon, 26 Apr 2021 03:19:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F91B611ED for ; Mon, 26 Apr 2021 03:19:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231782AbhDZDUC (ORCPT ); Sun, 25 Apr 2021 23:20:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39874 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231502AbhDZDUC (ORCPT ); Sun, 25 Apr 2021 23:20:02 -0400 Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A340C061760 for ; Sun, 25 Apr 2021 20:19:13 -0700 (PDT) Received: by mail-pf1-x42a.google.com with SMTP id y62so5374936pfg.4 for ; Sun, 25 Apr 2021 20:19:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sslab.ics.keio.ac.jp; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=1idmU5oasi5s8yake1E5MV/fuZG36GG+m+QfyCDPPAg=; b=FFBBiEbKdwEOvS0oHpkmceh8YwkI8JWzk9aEm6Q2tDb7iK0USLW0QEKvQG1ZV1P/N7 1ynXAijGp5Rvm//DBC+C5zYnIQmGDnQQMASRr8Tnlv271bcyXtY12nHSD+2I2PAl6+Ga OkXJOSqpveQOemOW3Ls3p2DmZP5lUBE4R/ncQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=1idmU5oasi5s8yake1E5MV/fuZG36GG+m+QfyCDPPAg=; b=WWKTAFyEUiq6397LEgU3ZSGzOA9hoUjYyFhuK2MUDSIaVABwMq/Ia09aXsRBgwhxgR Xvk93VZgoRHwwX72gM4lONi67SudcCZtSCs+CvIKa2Po8kuxoWMPcI0QOgA58MqI26kS 4/lUACmjdVHl+YIGVm8/9uSjKNXtELVoUy3+gr+XgsIIBynoyn7pcP5MfasX+mb8+6NZ 30CaI1qqFNmnLmFWva5GjEgGXYJ0VF81xzYIqZHu2AAjuKGrvjj/HLuZHV2waYN+DtgA 1HY8/yh/aRAaZjuc0AhC/n9Hj6eHHAkMdSg6Wu8CrKPGVzLOuILAcQwbt5MDhpFuTBXm HN+A== X-Gm-Message-State: AOAM533rf6ymfngxYmtRidb9nMOVO7ZMtEI+es4VpQXzug9BaG3kq0D3 Lfdua7rXnh8mSvhoy0tlswnqSHFsbgwQlwXQyrc= X-Google-Smtp-Source: ABdhPJw2NvtElpce5Tsiply0Pczv0FCmrOEKJ1UaVHlZ+QzzAJJ0woA/MGNFNFMfXQxSQ5/2tsFmNg== X-Received: by 2002:a65:56cc:: with SMTP id w12mr14980759pgs.334.1619407153036; Sun, 25 Apr 2021 20:19:13 -0700 (PDT) Received: from haraichi.dnlocal (113x36x239x145.ap113.ftth.ucom.ne.jp. [113.36.239.145]) by smtp.googlemail.com with ESMTPSA id s32sm96035pfw.2.2021.04.25.20.19.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Apr 2021 20:19:12 -0700 (PDT) From: Kenta Ishiguro To: kernellwp@gmail.com Cc: david@redhat.com, jmattson@google.com, joro@8bytes.org, kentaishiguro@sslab.ics.keio.ac.jp, kono@sslab.ics.keio.ac.jp, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, pl@sslab.ics.keio.ac.jp, seanjc@google.com, vkuznets@redhat.com, wanpengli@tencent.com Subject: Re: [RFC PATCH 0/2] Mitigating Excessive Pause-Loop Exiting in VM-Agnostic KVM Date: Mon, 26 Apr 2021 12:18:58 +0900 Message-Id: <20210426031858.12003-1-kentaishiguro@sslab.ics.keio.ac.jp> X-Mailer: git-send-email 2.30.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Thank you for the reply. My question is about following scenario: 1. running vCPU receives IPI and the vCPU's ipi_received gets true 2. the vCPU responds to the IPI 3. the vCPU exits 4. the vCPU is preempted by KVM 5. the vCPU is boosted, but it has already responded to the IPI 6. the vCPU enters and the vCPU's ipi_received is cleaned In this case, I think the check of vcpu->preempted does not limit the candidate vCPUs.