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Mon, 2 Sep 2024 15:06:08 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BD8D72004B; Mon, 2 Sep 2024 15:06:08 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8F94D20043; Mon, 2 Sep 2024 15:06:08 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 2 Sep 2024 15:06:08 +0000 (GMT) From: Mete Durlu To: kzak@redhat.com Cc: util-linux@vger.kernel.org, hca@linux.ibm.com Subject: [PATCH 2/2] chcpu(8): Document CPU deconfiguring behavior Date: Mon, 2 Sep 2024 17:05:53 +0200 Message-ID: <20240902150553.1969571-3-meted@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240902150553.1969571-1-meted@linux.ibm.com> References: <20240902150553.1969571-1-meted@linux.ibm.com> Precedence: bulk X-Mailing-List: util-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: bNP1t8_N7xJ2DGfejj1zEuXXLoFJt8k6 X-Proofpoint-GUID: kTQ9mkinWFk1E-4GYPq3d3SyxbbtTPPw X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-02_04,2024-09-02_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 bulkscore=0 mlxscore=0 clxscore=1015 malwarescore=0 lowpriorityscore=0 adultscore=0 spamscore=0 phishscore=0 mlxlogscore=895 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2407110000 definitions=main-2409020119 If architecture supports (de)configuring CPUs, the user should deconfigure disabled CPUs to prevent performance penalties. Signed-off-by: Mete Durlu --- sys-utils/chcpu.8.adoc | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sys-utils/chcpu.8.adoc b/sys-utils/chcpu.8.adoc index 0b0bcbc57..f08b5a6ab 100644 --- a/sys-utils/chcpu.8.adoc +++ b/sys-utils/chcpu.8.adoc @@ -39,6 +39,8 @@ Enable the specified CPUs. Enabling a CPU means that the kernel sets it online. Deconfigure the specified CPUs. Deconfiguring a CPU means that the hypervisor removes the CPU from the virtual hardware on which the Linux instance runs and returns it to the CPU pool. A CPU must be offline, see *-d*, before it can be deconfigured. + *chcpu -g* is not supported on IBM z/VM, CPUs are always in a configured state. ++ +if *chcpu -g* is supported, any *disabled* CPUs should be *deconfigured* to inform the hypervisor that these CPUs won't be used, avoiding potential performance penalties. *-p*, *--dispatch* _mode_:: Set the CPU dispatching _mode_ (polarization). This option has an effect only if your hardware architecture and hypervisor support CPU polarization. Available _modes_ are: -- 2.46.0