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Thu, 3 Sep 2026 06:34:40 +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 v12 13/13] virt/steal_governor: Enable the driver Date: Thu, 3 Sep 2026 12:02:40 +0530 Message-ID: <20260903063240.268775-14-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260903063240.268775-1-sshegde@linux.ibm.com> References: <20260903063240.268775-1-sshegde@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@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-Authority-Analysis: v=2.4 cv=PPc/P/qC c=1 sm=1 tr=0 ts=6a99150f cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=jPZz8W9ceouySDeeKuAA:9 X-Proofpoint-GUID: 8jmbw4Nw_27ku6VuTzGCQWkEy4_5J3-J X-Proofpoint-ORIG-GUID: bFa-iy32QYLkbHUQxW9ewRqS5ISAQxaM X-Proofpoint-Spam-Info: AW1haW4tMjYwOTAzMDA1NyBTYWx0ZWRfX1Xt3wXeKIa7E SSGcDNnIMeseKPwrUFGe7Dwt9U0CCwBXyyK5EyUi80xvw2gLNzQpdwtoQg7/FBhu/q8hBfKZUCS WA+S1mruMLLdfkJwGsfDZvsVa4PEGfw= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTAzMDA1NyBTYWx0ZWRfXyY6oQJi+BVM/ Jifg2iCRzeZWCyuMcfUkUWdxNP9RAcJoVNEDQCbJL0KUCXHUVpQcvf1UqVYH/Iju+s8VUcw4AM6 +zs2itv/owysnF0lrYycx62lR0h0A3/laKgA4ILcBVRx+IzFv7DLmLmpP9x+3dz3lxM90h1j9XH NqDef45LFBKBYShxhA9CGS4VvQ0mzfc2tIi4VwV7HaLHnZJI+v5JEgcLgt9WcAN92fqtvztLQgp BQRku1NXFEEPSAkE1/l/++6ufMAeElnbN0QGJ0jVP1kVV4wGhFj7x9kVaDWOcVm6MlRVZUh8jT5 /T3EPMhHdalF7flC1SRqYm9/LACSd8kv9YcWCvmL3XM8AAqFhdVuBVRlpANAgaaoIpNn7aUDCVm qVPuje6xEmeQU22XuZ+2h7beOHi6m1vVdTQ/uaQqIMZwTcy0XcJMhbVX7WRuNjv02BYXcPpqGB6 NXkilu0W8u7EeuZKRxw== 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=2026-09-03_02,2026-09-02_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 phishscore=0 adultscore=0 suspectscore=0 bulkscore=0 spamscore=0 priorityscore=1501 impostorscore=0 malwarescore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609030057 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/ -- 2.52.0