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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 AA7DEC433EF for ; Wed, 15 Sep 2021 01:42:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8064760F6C for ; Wed, 15 Sep 2021 01:42:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230408AbhIOBne (ORCPT ); Tue, 14 Sep 2021 21:43:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54340 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229491AbhIOBne (ORCPT ); Tue, 14 Sep 2021 21:43:34 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E78FC061574 for ; Tue, 14 Sep 2021 18:42:16 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id f11-20020a17090aa78b00b0018e98a7cddaso1035201pjq.4 for ; Tue, 14 Sep 2021 18:42:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=DysTSQ9MR7/MaAx/pRLkL6jfnSsn9VkFolBRT1eG9zQ=; b=AUOBu9K/jEuUJpiOvBO7L4C+bbOipNOOARov/eL8Z8HmZLjQB0lvKMIx8yyUHXVGGy 0tQNsA+x6B0PTYIZ9wYWNWA7v/b7ulJoZGujv/TE11jiCkXu1ZmJ7HtyCSrOlT9cXzBe ITmyz/eQmg86aCpAbXeQM+37NEH3DR82ha8zw= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=DysTSQ9MR7/MaAx/pRLkL6jfnSsn9VkFolBRT1eG9zQ=; b=oeoY9aEomWsOJDUEBspZEZzRfxcd6cz9MgpANdthyQDSDOgR7WCmqx6D6l8fiiCUkI 5L1hgHDEeKV+DUzZi4p/O8LSYtFn5UWdyjIJ3RtIgIWdCNnd/+Hrl++6qLWWJRAu10De FLa3CNamCDg/WCA645sv1i+EWjAZwpp9dXl4kT7XsnmmmAYxN5SUIff2rwDqHH2/m64R HY+q042TGRVJcAs/3lMCEyKAc7k2w5O9HHp9yCiDVs4WFDMBc/z5N8dOvmAj/5jYSSBh cVafI+JkXMnG+91qRyhvnGXD0yRouiEaT3F58DtXOD2DARTtCVAtWECctivvmJq6+SPT 8Slw== X-Gm-Message-State: AOAM5311rcvC/wzJvJUV//+qNOdFnhfSseeY2w2JFh4nEcjLhTCArbxA 1tudwq+DwRFc0NQBqTs7UHyhYQ== X-Google-Smtp-Source: ABdhPJzG8S5razlemYl4/wsU1GAIJmc3xfvr4CWPNLXu1XAJ2sAk+M1QRs67/BUASP5QiGulz3r2FQ== X-Received: by 2002:a17:90b:1c87:: with SMTP id oo7mr5396576pjb.163.1631670135635; Tue, 14 Sep 2021 18:42:15 -0700 (PDT) Received: from google.com ([2409:10:2e40:5100:e3e3:41c9:dd51:5a4f]) by smtp.gmail.com with ESMTPSA id 23sm3195056pfp.206.2021.09.14.18.42.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Sep 2021 18:42:14 -0700 (PDT) Date: Wed, 15 Sep 2021 10:42:10 +0900 From: Sergey Senozhatsky To: Paolo Bonzini Cc: Suleiman Souhlal , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: Re: [PATCH] KVM: do not shrink halt_poll_ns below grow_start Message-ID: References: <20210902031100.252080-1-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210902031100.252080-1-senozhatsky@chromium.org> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On (21/09/02 12:11), Sergey Senozhatsky wrote: > grow_halt_poll_ns() ignores values between 0 and > halt_poll_ns_grow_start (10000 by default). However, > when we shrink halt_poll_ns we may fall way below > halt_poll_ns_grow_start and endup with halt_poll_ns > values that don't make a lot of sense: like 1 or 9, > or 19. > > VCPU1 trace (halt_poll_ns_shrink equals 2): > > VCPU1 grow 10000 > VCPU1 shrink 5000 > VCPU1 shrink 2500 > VCPU1 shrink 1250 > VCPU1 shrink 625 > VCPU1 shrink 312 > VCPU1 shrink 156 > VCPU1 shrink 78 > VCPU1 shrink 39 > VCPU1 shrink 19 > VCPU1 shrink 9 > VCPU1 shrink 4 > > Mirror what grow_halt_poll_ns() does and set halt_poll_ns > to 0 as soon as new shrink-ed halt_poll_ns value falls > below halt_poll_ns_grow_start. Gentle ping. -ss