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=ham 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 C286AC433B4 for ; Mon, 26 Apr 2021 03:19:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C0F1611C1 for ; Mon, 26 Apr 2021 03:19:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231773AbhDZDT4 (ORCPT ); Sun, 25 Apr 2021 23:19:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39872 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231502AbhDZDTz (ORCPT ); Sun, 25 Apr 2021 23:19:55 -0400 Received: from mail-pf1-x42c.google.com (mail-pf1-x42c.google.com [IPv6:2607:f8b0:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 802E2C061574 for ; Sun, 25 Apr 2021 20:19:13 -0700 (PDT) Received: by mail-pf1-x42c.google.com with SMTP id 10so2590700pfl.1 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=BjMBeklKxO56WvC+EXd3TNofSPXGgE9oCZ36nDiDPI/rBbwEtTg+0Z4cZRd7j58eMJ FLfa+1JlGnwNr1SPPfNHivLyZQlWnAdRyXyOv44eQONFicJPe9sSw5lUSwwrdRWgGv/R 8vrIHJ0E0ptaAE8c9gjYeNQocalJC+1WEH1RbEbZ9M1VvvtaOyxxtotrg+hsiSn6Z0uG FCppI7FRMxZpKU8to+PY9j2ZHHUOtT5T08LgSICrPfnyt+z+XCOhm41qzxE4P2jHYDtx nOA6hpnAg8dPKYY5bRkVprnfiDoEMV0vpGtfj1Zj/xivRYAo2QpFKH0umwieIH1V3uIY pvnQ== X-Gm-Message-State: AOAM531mCUFA+A5DSo+aBFD4odejunS2+OupFLyrvixBAW3LIg0KbKmy DIPFwbfj3mdh6j0OEauvgKonww== 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: linux-kernel@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.