From: kernel test robot <lkp@intel.com>
To: Wanpeng Li <kernellwp@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>
Cc: oe-kbuild-all@lists.linux.dev,
K Prateek Nayak <kprateek.nayak@amd.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Juri Lelli <juri.lelli@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Wanpeng Li <wanpengli@tencent.com>
Subject: Re: [PATCH v2 5/9] sched/fair: Wire up yield deboost in yield_to_task_fair()
Date: Mon, 22 Dec 2025 17:31:23 +0800 [thread overview]
Message-ID: <202512221734.SzKNollL-lkp@intel.com> (raw)
In-Reply-To: <20251219035334.39790-6-kernellwp@gmail.com>
Hi Wanpeng,
kernel test robot noticed the following build errors:
[auto build test ERROR on kvm/queue]
[also build test ERROR on kvm/next tip/sched/core peterz-queue/sched/core tip/master linus/master v6.19-rc2 next-20251219]
[cannot apply to kvm/linux-next tip/auto-latest]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Wanpeng-Li/sched-fair-Add-rate-limiting-and-validation-helpers/20251219-125353
base: https://git.kernel.org/pub/scm/virt/kvm/kvm.git queue
patch link: https://lore.kernel.org/r/20251219035334.39790-6-kernellwp%40gmail.com
patch subject: [PATCH v2 5/9] sched/fair: Wire up yield deboost in yield_to_task_fair()
config: i386-randconfig-003-20251222 (https://download.01.org/0day-ci/archive/20251222/202512221734.SzKNollL-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.4.0-5) 12.4.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251222/202512221734.SzKNollL-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512221734.SzKNollL-lkp@intel.com/
All errors (new ones prefixed by >>):
ld: kernel/sched/fair.o: in function `yield_deboost_calculate_penalty':
>> kernel/sched/fair.c:9213:(.text+0x278d): undefined reference to `__udivdi3'
vim +9213 kernel/sched/fair.c
9a700d273608de Wanpeng Li 2025-12-19 9176
9a700d273608de Wanpeng Li 2025-12-19 9177 /*
9a700d273608de Wanpeng Li 2025-12-19 9178 * Calculate vruntime penalty for yield deboost.
9a700d273608de Wanpeng Li 2025-12-19 9179 *
9a700d273608de Wanpeng Li 2025-12-19 9180 * The penalty is based on:
9a700d273608de Wanpeng Li 2025-12-19 9181 * - Fairness gap: vruntime difference between yielding and target tasks
9a700d273608de Wanpeng Li 2025-12-19 9182 * - Scheduling granularity: base unit for penalty calculation
9a700d273608de Wanpeng Li 2025-12-19 9183 * - Queue size: adaptive caps to prevent starvation in larger queues
9a700d273608de Wanpeng Li 2025-12-19 9184 *
9a700d273608de Wanpeng Li 2025-12-19 9185 * Queue-size-based caps (multiplier of granularity):
9a700d273608de Wanpeng Li 2025-12-19 9186 * 2 tasks: 6.0x - Strongest push for 2-task ping-pong scenarios
9a700d273608de Wanpeng Li 2025-12-19 9187 * 3 tasks: 4.0x
9a700d273608de Wanpeng Li 2025-12-19 9188 * 4-6: 2.5x
9a700d273608de Wanpeng Li 2025-12-19 9189 * 7-8: 2.0x
9a700d273608de Wanpeng Li 2025-12-19 9190 * 9-12: 1.5x
9a700d273608de Wanpeng Li 2025-12-19 9191 * >12: 1.0x - Minimal push to avoid starvation
9a700d273608de Wanpeng Li 2025-12-19 9192 *
9a700d273608de Wanpeng Li 2025-12-19 9193 * Returns the calculated penalty value.
9a700d273608de Wanpeng Li 2025-12-19 9194 */
9a700d273608de Wanpeng Li 2025-12-19 9195 static u64 __maybe_unused
9a700d273608de Wanpeng Li 2025-12-19 9196 yield_deboost_calculate_penalty(struct rq *rq, struct sched_entity *se_y_lca,
9a700d273608de Wanpeng Li 2025-12-19 9197 struct sched_entity *se_t_lca,
9a700d273608de Wanpeng Li 2025-12-19 9198 struct task_struct *p_target, int h_nr_queued)
9a700d273608de Wanpeng Li 2025-12-19 9199 {
9a700d273608de Wanpeng Li 2025-12-19 9200 u64 gran, need, penalty, maxp;
9a700d273608de Wanpeng Li 2025-12-19 9201 u64 weighted_need, base;
9a700d273608de Wanpeng Li 2025-12-19 9202
9a700d273608de Wanpeng Li 2025-12-19 9203 gran = calc_delta_fair(sysctl_sched_base_slice, se_y_lca);
9a700d273608de Wanpeng Li 2025-12-19 9204
9a700d273608de Wanpeng Li 2025-12-19 9205 /* Calculate fairness gap */
9a700d273608de Wanpeng Li 2025-12-19 9206 need = 0;
9a700d273608de Wanpeng Li 2025-12-19 9207 if (se_t_lca->vruntime > se_y_lca->vruntime)
9a700d273608de Wanpeng Li 2025-12-19 9208 need = se_t_lca->vruntime - se_y_lca->vruntime;
9a700d273608de Wanpeng Li 2025-12-19 9209
9a700d273608de Wanpeng Li 2025-12-19 9210 /* Base penalty is granularity plus 110% of fairness gap */
9a700d273608de Wanpeng Li 2025-12-19 9211 penalty = gran;
9a700d273608de Wanpeng Li 2025-12-19 9212 if (need) {
9a700d273608de Wanpeng Li 2025-12-19 @9213 weighted_need = need + need / 10;
9a700d273608de Wanpeng Li 2025-12-19 9214 if (weighted_need > U64_MAX - penalty)
9a700d273608de Wanpeng Li 2025-12-19 9215 weighted_need = U64_MAX - penalty;
9a700d273608de Wanpeng Li 2025-12-19 9216 penalty += weighted_need;
9a700d273608de Wanpeng Li 2025-12-19 9217 }
9a700d273608de Wanpeng Li 2025-12-19 9218
9a700d273608de Wanpeng Li 2025-12-19 9219 /* Apply debounce to reduce ping-pong */
9a700d273608de Wanpeng Li 2025-12-19 9220 penalty = yield_deboost_apply_debounce(rq, p_target, penalty, need, gran);
9a700d273608de Wanpeng Li 2025-12-19 9221
9a700d273608de Wanpeng Li 2025-12-19 9222 /* Queue-size-based upper bound */
9a700d273608de Wanpeng Li 2025-12-19 9223 if (h_nr_queued == 2)
9a700d273608de Wanpeng Li 2025-12-19 9224 maxp = gran * 6;
9a700d273608de Wanpeng Li 2025-12-19 9225 else if (h_nr_queued == 3)
9a700d273608de Wanpeng Li 2025-12-19 9226 maxp = gran * 4;
9a700d273608de Wanpeng Li 2025-12-19 9227 else if (h_nr_queued <= 6)
9a700d273608de Wanpeng Li 2025-12-19 9228 maxp = (gran * 5) / 2;
9a700d273608de Wanpeng Li 2025-12-19 9229 else if (h_nr_queued <= 8)
9a700d273608de Wanpeng Li 2025-12-19 9230 maxp = gran * 2;
9a700d273608de Wanpeng Li 2025-12-19 9231 else if (h_nr_queued <= 12)
9a700d273608de Wanpeng Li 2025-12-19 9232 maxp = (gran * 3) / 2;
9a700d273608de Wanpeng Li 2025-12-19 9233 else
9a700d273608de Wanpeng Li 2025-12-19 9234 maxp = gran;
9a700d273608de Wanpeng Li 2025-12-19 9235
9a700d273608de Wanpeng Li 2025-12-19 9236 penalty = clamp(penalty, gran, maxp);
9a700d273608de Wanpeng Li 2025-12-19 9237
9a700d273608de Wanpeng Li 2025-12-19 9238 /* Baseline push when no fairness gap exists */
9a700d273608de Wanpeng Li 2025-12-19 9239 if (need == 0) {
9a700d273608de Wanpeng Li 2025-12-19 9240 if (h_nr_queued == 3)
9a700d273608de Wanpeng Li 2025-12-19 9241 base = (gran * 15) / 16;
9a700d273608de Wanpeng Li 2025-12-19 9242 else if (h_nr_queued >= 4 && h_nr_queued <= 6)
9a700d273608de Wanpeng Li 2025-12-19 9243 base = (gran * 5) / 8;
9a700d273608de Wanpeng Li 2025-12-19 9244 else if (h_nr_queued >= 7 && h_nr_queued <= 8)
9a700d273608de Wanpeng Li 2025-12-19 9245 base = gran / 2;
9a700d273608de Wanpeng Li 2025-12-19 9246 else if (h_nr_queued >= 9 && h_nr_queued <= 12)
9a700d273608de Wanpeng Li 2025-12-19 9247 base = (gran * 3) / 8;
9a700d273608de Wanpeng Li 2025-12-19 9248 else if (h_nr_queued > 12)
9a700d273608de Wanpeng Li 2025-12-19 9249 base = gran / 4;
9a700d273608de Wanpeng Li 2025-12-19 9250 else
9a700d273608de Wanpeng Li 2025-12-19 9251 base = gran;
9a700d273608de Wanpeng Li 2025-12-19 9252
9a700d273608de Wanpeng Li 2025-12-19 9253 if (penalty < base)
9a700d273608de Wanpeng Li 2025-12-19 9254 penalty = base;
9a700d273608de Wanpeng Li 2025-12-19 9255 }
9a700d273608de Wanpeng Li 2025-12-19 9256
9a700d273608de Wanpeng Li 2025-12-19 9257 return penalty;
9a700d273608de Wanpeng Li 2025-12-19 9258 }
9a700d273608de Wanpeng Li 2025-12-19 9259
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
next prev parent reply other threads:[~2025-12-22 9:31 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-19 3:53 [PATCH v2 0/9] sched/kvm: Semantics-aware vCPU scheduling for oversubscribed KVM Wanpeng Li
2025-12-19 3:53 ` [PATCH v2 1/9] sched: Add vCPU debooster infrastructure Wanpeng Li
2025-12-19 3:53 ` [PATCH v2 2/9] sched/fair: Add rate-limiting and validation helpers Wanpeng Li
2025-12-22 21:12 ` kernel test robot
2026-01-04 4:09 ` Hillf Danton
2025-12-19 3:53 ` [PATCH v2 3/9] sched/fair: Add cgroup LCA finder for hierarchical yield Wanpeng Li
2025-12-19 3:53 ` [PATCH v2 4/9] sched/fair: Add penalty calculation and application logic Wanpeng Li
2025-12-22 23:36 ` kernel test robot
2025-12-19 3:53 ` [PATCH v2 5/9] sched/fair: Wire up yield deboost in yield_to_task_fair() Wanpeng Li
2025-12-22 7:06 ` kernel test robot
2025-12-22 9:31 ` kernel test robot [this message]
2025-12-19 3:53 ` [PATCH v2 6/9] KVM: x86: Add IPI tracking infrastructure Wanpeng Li
2025-12-19 3:53 ` [PATCH v2 7/9] KVM: x86/lapic: Integrate IPI tracking with interrupt delivery Wanpeng Li
2025-12-19 3:53 ` [PATCH v2 8/9] KVM: Implement IPI-aware directed yield candidate selection Wanpeng Li
2025-12-19 3:53 ` [PATCH v2 9/9] KVM: Relaxed boost as safety net Wanpeng Li
2026-01-04 2:40 ` [PATCH v2 0/9] sched/kvm: Semantics-aware vCPU scheduling for oversubscribed KVM Wanpeng Li
2026-01-05 6:26 ` K Prateek Nayak
2026-03-13 1:13 ` Sean Christopherson
2026-04-01 9:48 ` Wanpeng Li
2026-04-02 23:43 ` Sean Christopherson
2026-03-26 14:41 ` Christian Borntraeger
2026-04-01 9:34 ` Wanpeng Li
2026-04-08 9:35 ` Richie Buturla
2026-04-17 11:30 ` Richie Buturla
2026-05-13 12:52 ` Richie Buturla
2026-06-12 14:07 ` Wanpeng Li
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