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Tue, 25 Aug 2026 10:41:15 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.39.21.103]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 25 Aug 2026 10:41:15 +0000 (GMT) From: Shrikanth Hegde To: linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, yury.norov@gmail.com, kprateek.nayak@amd.com, iii@linux.ibm.com, corbet@lwn.net, meted@linux.ibm.com, ynorov@nvidia.com Cc: sshegde@linux.ibm.com, tglx@kernel.org, gregkh@linuxfoundation.org, pbonzini@redhat.com, seanjc@google.com, vschneid@redhat.com, huschle@linux.ibm.com, rostedt@goodmis.org, dietmar.eggemann@arm.com, maddy@linux.ibm.com, srikar@linux.ibm.com, hdanton@sina.com, chleroy@kernel.org, vineeth@bitbyteword.org, frederic@kernel.org, arighi@nvidia.com, pauld@redhat.com, christian.loehle@arm.com, tj@kernel.org, tommaso.cucinotta@gmail.com, maz@kernel.org, rafael@kernel.org, rdunlap@infradead.org, kernellwp@gmail.com, linux-doc@vger.kernel.org, jgross@suse.com, virtualization@lists.linux.dev, sunlightlinux@gmail.com Subject: [PATCH v11 12/12] virt/steal_governor: Enable the driver Date: Tue, 25 Aug 2026 16:08:55 +0530 Message-ID: <20260825103855.721013-13-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260825103855.721013-1-sshegde@linux.ibm.com> References: <20260825103855.721013-1-sshegde@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: jNZWDPDln-panWY0jQfd4q1GEeQT3aQ6 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI1MDA4OSBTYWx0ZWRfXwj+8FK1K2xXP bfbImwah28054Zk70hsV/JoOIfwWCdDOvJvRvi44u5Apcckb40AqImEHMonowzf9SG820iQ8bk8 6pBFo4etul4dp2MIggPSdG1AmM5JCY8C8aHOrZsl3MiqObdmP2A5gRlDXx2IU8QdpO40MTySlj3 MkX0GKKBGdKpOd0LMxBCO1NY/eOn10LVJn9OqrR0FA0BJPbmnjibeS+KsMY6O/zQc2Q9dyvT+3r uIpIF+0mLsvEj+Gd+EgszSwcQ9IWSqhRXcUi4PR0aCb1b6hcgkzKZcwqHsRdWFNQD7ITUWqhJIU HnoumIz/8HbqnwfLNidIt4jYlAnMNV1edzcqqICzWpWC6ec5GSnXDxQ45lA6GflGP/v8ubgrL01 cUkNLOCFwDv8sDcLDkzZtIUYEOOYI5UCAf7FXw2imhYnv3FeQofYNXZ3WtjUyeouQ5YJjYdUlyv 8jEBiiMDBoYT+0qgtFw== X-Authority-Analysis: v=2.4 cv=Y/nIdBeN c=1 sm=1 tr=0 ts=6a8d715a cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=jPZz8W9ceouySDeeKuAA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI1MDA4OSBTYWx0ZWRfXzMnKBx3yS1IU gCyuwsIrPF3Iu7wF52ikDZ/f8gJhYxc5Lgw0naLKKxZL1qWJiKGLM0pfItXOHrXtvfHIWdYLRmw 3wWvaJTZOZaqm8Urxm7gokIp481bd+8= X-Proofpoint-ORIG-GUID: K76MRLkoU62FVnXVYZFQ5c3J2NKE2_LM X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-25_02,2026-08-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 priorityscore=1501 adultscore=0 bulkscore=0 suspectscore=0 malwarescore=0 clxscore=1015 lowpriorityscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608250089 Provide a config option to enable the steal_governor driver. Since the feature targets paravirtualized environments and requires SMP, enforce those dependencies. The driver selects CONFIG_PREFERRED_CPU for the core scheduler mechanisms to work. It is recommended to build the driver as a module (m) instead of built-in (y) due to the following reasons: - Module parameters are read-only after initialization. Building as a module allows updating these parameters by simply reloading the module. Default module parameters cannot work in all configurations. - The driver can be completely disabled by unloading the module. - This feature works best when all VMs operate in a cooperative manner. Requiring an explicit module load ensures intentional deployment across all VMs by the system administrator. Suggested-by: Yury Norov Signed-off-by: Shrikanth Hegde --- drivers/virt/Kconfig | 17 +++++++++++++++++ drivers/virt/Makefile | 1 + 2 files changed, 18 insertions(+) diff --git a/drivers/virt/Kconfig b/drivers/virt/Kconfig index 52eb7e4ba71f..eeb84e578ddf 100644 --- a/drivers/virt/Kconfig +++ b/drivers/virt/Kconfig @@ -41,6 +41,23 @@ config FSL_HV_MANAGER 4) A kernel interface for receiving callbacks when a managed partition shuts down. +config STEAL_GOVERNOR + tristate "Dynamic vCPU management based on steal time" + depends on PARAVIRT && SMP + select PREFERRED_CPU + default m + help + This driver helps to reduce the steal time in paravirtualized + environments, thereby reducing vCPU preemption costs. + + By default preferred CPUs will be same as active CPUs. Depending + on the steal time when steal_governor driver is enabled, + preferred CPUs could become subset of active CPUs. + More details are at: Documentation/driver-api/steal-governor.rst + + It is recommended to build it as module and load the module + to enable it. + source "drivers/virt/vboxguest/Kconfig" source "drivers/virt/nitro_enclaves/Kconfig" diff --git a/drivers/virt/Makefile b/drivers/virt/Makefile index f29901bd7820..05fb075ef5b8 100644 --- a/drivers/virt/Makefile +++ b/drivers/virt/Makefile @@ -5,6 +5,7 @@ obj-$(CONFIG_FSL_HV_MANAGER) += fsl_hypervisor.o obj-$(CONFIG_VMGENID) += vmgenid.o +obj-$(CONFIG_STEAL_GOVERNOR) += steal_governor.o obj-y += vboxguest/ obj-$(CONFIG_NITRO_ENCLAVES) += nitro_enclaves/ -- 2.47.3