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Wed, 1 Jul 2026 14:20:45 +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 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 Subject: [PATCH v6 16/23] virt/steal_monitor: Compute work at regular intervals Date: Wed, 1 Jul 2026 19:46:47 +0530 Message-ID: <20260701141654.500125-17-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260701141654.500125-1-sshegde@linux.ibm.com> References: <20260701141654.500125-1-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: 0cWP6BE3kFMNgrWUiFDX3FQoNfYVbDho X-Proofpoint-Spam-Info: AW1haW4tMjYwNzAxMDE1MCBTYWx0ZWRfXxoQtYNKz8H3M N6XgUTjoqOhghcuDYltVnRX7y2i40wD8hmTixTiEdLJK3VJwm7kktw4W/fScwPyc2aRx1FqWMeK WnnKQhZPvKAWce/D7EU0jd8zJ0sEZSk= X-Authority-Analysis: v=2.4 cv=edsNubEH c=1 sm=1 tr=0 ts=6a452250 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=FaF7mGpESULvgM3RsB4A:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzAxMDE1MCBTYWx0ZWRfX7rUOEk5cwhiF zz+8NQ/u1nwgfrCYVO9M0hEMrX3Xvoc62EDorhA2SMvB3xVDmJyuXvPPOp1tKrHn88Ej2GXKwBt /8mcjs2lkeEdCHkKes/s9lJ9O3r6CBzFmir877CM24cOdgOpT5P548WzwLG092NvAr0jgkIyjPW rigK0cMv9g7bwu86I0rmowS7qo4iwrMPx9cCctTUTqLIskFMpqqBkx2kXrARKGCXGziQ9Aws7kQ GcJUmFxGcI8xUm6GzWp8XmT98yVp70bWP+kCfs4Q5SGtfoAv+QqKJbAQpCwAE4HberM6Dzy7P+9 aMjPCI0W87SHxmLvXyQz2GdYClFk8vhv6til6Fa3Hx6Eg3nARROptZp9CQCTCqdA54EiRSgPHTi 23ghJuWOH5IcIyMieweGWUlpOa48WoYoQad+abnkpmj/xFLJouFUjSgR1ozrQnDPSS2r0dLHt91 9Adh3N0zilLY5jqrLmA== X-Proofpoint-ORIG-GUID: kBwWJN7W-ZXbDLAQPN1SKmCMG4oAov9y X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-07-01_03,2026-06-26_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 adultscore=0 impostorscore=0 bulkscore=0 spamscore=0 suspectscore=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-2607010150 This is the steal_monitor core functionality done in periodic work - Calculate the steal_ratio. It is multiplied by 100 to consider the fractional values of steal time. I.e 10 means 0.1% steal time. - If steal value is higher than high threshold, call the method to reduce the preferred CPUs. - If steal value is lower or equal to low threshold, call the method to increase the preferred CPUs. - If the steal value is in between, no action is taken. - Save the values for next delta calculations. Signed-off-by: Shrikanth Hegde --- drivers/virt/steal_monitor/sm_core.c | 26 +++++++++++++++++++++++++- drivers/virt/steal_monitor/sm_core.h | 3 +++ 2 files changed, 28 insertions(+), 1 deletion(-) diff --git a/drivers/virt/steal_monitor/sm_core.c b/drivers/virt/steal_monitor/sm_core.c index 1ba638224abb..b499faa61010 100644 --- a/drivers/virt/steal_monitor/sm_core.c +++ b/drivers/virt/steal_monitor/sm_core.c @@ -32,9 +32,32 @@ module_param_named(low_threshold, sm_core_ctx.low_threshold, uint, 0644); MODULE_PARM_DESC(low_threshold, "Low steal threshold (default: 200 i.e 2%)"); +static void compute_preferred_cpus_work(struct work_struct *work) +{ + /* At least one core is kept as preferred */ + WARN_ON(cpumask_empty(cpu_preferred_mask)); + + /* Warn if interval_ms is set to 0, that might cause lockup. */ + if (unlikely(sm_core_ctx.interval_ms == 0)) { + WARN_ON(1); + sm_core_ctx.interval_ms = 1000; /* Fallback to default */ + } + + /* Trigger for next sampling */ + schedule_delayed_work(&sm_core_ctx.work, + msecs_to_jiffies(sm_core_ctx.interval_ms)); +} + static int __init steal_monitor_init(void) { - pr_info("steal_monitor is enabled\n"); + pr_info("steal_monitor is enabled. interval: %ums, high_threshold: %u, low_threshold: %u\n", + sm_core_ctx.interval_ms, sm_core_ctx.high_threshold, sm_core_ctx.low_threshold); + + INIT_DELAYED_WORK(&sm_core_ctx.work, compute_preferred_cpus_work); + + schedule_delayed_work(&sm_core_ctx.work, + msecs_to_jiffies(sm_core_ctx.interval_ms)); + return 0; } @@ -42,6 +65,7 @@ static void __exit steal_monitor_exit(void) { pr_info("steal_monitor is disabled\n"); + cancel_delayed_work_sync(&sm_core_ctx.work); guard(cpus_read_lock)(); cpumask_copy(&__cpu_preferred_mask, cpu_active_mask); } diff --git a/drivers/virt/steal_monitor/sm_core.h b/drivers/virt/steal_monitor/sm_core.h index e5c3ea0a63c9..ea06e83c228c 100644 --- a/drivers/virt/steal_monitor/sm_core.h +++ b/drivers/virt/steal_monitor/sm_core.h @@ -8,6 +8,9 @@ #include #include #include +#include +#include +#include struct steal_monitor { struct delayed_work work; -- 2.47.3