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([2001:b07:6468:f312:a0f7:472a:1e7:7ef]) by smtp.gmail.com with ESMTPSA id 200sm27687037wme.32.2019.11.11.05.54.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Nov 2019 05:54:45 -0800 (PST) Subject: Re: [PATCH 4/5] cpuidle-haltpoll: add a check to ensure grow start value is nonzero To: Zhenzhong Duan , Marcelo Tosatti Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, joao.m.martins@oracle.com, rafael.j.wysocki@intel.com, rkrcmar@redhat.com References: <1572060239-17401-1-git-send-email-zhenzhong.duan@oracle.com> <1572060239-17401-5-git-send-email-zhenzhong.duan@oracle.com> <20191101211908.GA20672@amt.cnet> <7245089f-788e-03d6-9833-6ce4d313f4ce@oracle.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <57679389-6e4a-b7ad-559f-3128a608c28a@redhat.com> Date: Mon, 11 Nov 2019 14:54:47 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <7245089f-788e-03d6-9833-6ce4d313f4ce@oracle.com> Content-Language: en-US X-MC-Unique: xfu9xFBdOUGSEJCcrNvAPg-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/11/19 03:56, Zhenzhong Duan wrote: >=20 > On 2019/11/2 5:19, Marcelo Tosatti wrote: >> On Sat, Oct 26, 2019 at 11:23:58AM +0800, Zhenzhong Duan wrote: >>> dev->poll_limit_ns could be zeroed in certain cases (e.g. by >>> guest_halt_poll_shrink). If guest_halt_poll_grow_start is zero, >>> dev->poll_limit_ns will never be larger than zero. >>> >>> Signed-off-by: Zhenzhong Duan >>> --- >>> =A0 drivers/cpuidle/governors/haltpoll.c | 15 ++++++++++++--- >>> =A0 1 file changed, 12 insertions(+), 3 deletions(-) >> I would rather disallow setting grow_start to zero rather >> than silently setting it to one on the back of the user. >=20 > Ok, will do. Similar to patch 2, I think disabling halt polling is a good behavior if grow_start =3D 0. Paolo