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1/* SPDX-License-Identifier: GPL-2.0 */2/*3 * A scheduler that validates that enqueue flags are properly stored and4 * applied at dispatch time when a task is directly dispatched from5 * ops.select_cpu(). We validate this by using scx_bpf_dispatch_vtime(), and6 * making the test a very basic vtime scheduler.7 *8 * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.9 * Copyright (c) 2024 David Vernet <dvernet@meta.com>10 * Copyright (c) 2024 Tejun Heo <tj@kernel.org>11 */12 13#include <scx/common.bpf.h>14 15char _license[] SEC("license") = "GPL";16 17volatile bool consumed;18 19static u64 vtime_now;20 21#define VTIME_DSQ 022 23static inline bool vtime_before(u64 a, u64 b)24{25 return (s64)(a - b) < 0;26}27 28static inline u64 task_vtime(const struct task_struct *p)29{30 u64 vtime = p->scx.dsq_vtime;31 32 if (vtime_before(vtime, vtime_now - SCX_SLICE_DFL))33 return vtime_now - SCX_SLICE_DFL;34 else35 return vtime;36}37 38s32 BPF_STRUCT_OPS(select_cpu_vtime_select_cpu, struct task_struct *p,39 s32 prev_cpu, u64 wake_flags)40{41 s32 cpu;42 43 cpu = scx_bpf_pick_idle_cpu(p->cpus_ptr, 0);44 if (cpu >= 0)45 goto ddsp;46 47 cpu = prev_cpu;48 scx_bpf_test_and_clear_cpu_idle(cpu);49ddsp:50 scx_bpf_dispatch_vtime(p, VTIME_DSQ, SCX_SLICE_DFL, task_vtime(p), 0);51 return cpu;52}53 54void BPF_STRUCT_OPS(select_cpu_vtime_dispatch, s32 cpu, struct task_struct *p)55{56 if (scx_bpf_consume(VTIME_DSQ))57 consumed = true;58}59 60void BPF_STRUCT_OPS(select_cpu_vtime_running, struct task_struct *p)61{62 if (vtime_before(vtime_now, p->scx.dsq_vtime))63 vtime_now = p->scx.dsq_vtime;64}65 66void BPF_STRUCT_OPS(select_cpu_vtime_stopping, struct task_struct *p,67 bool runnable)68{69 p->scx.dsq_vtime += (SCX_SLICE_DFL - p->scx.slice) * 100 / p->scx.weight;70}71 72void BPF_STRUCT_OPS(select_cpu_vtime_enable, struct task_struct *p)73{74 p->scx.dsq_vtime = vtime_now;75}76 77s32 BPF_STRUCT_OPS_SLEEPABLE(select_cpu_vtime_init)78{79 return scx_bpf_create_dsq(VTIME_DSQ, -1);80}81 82SEC(".struct_ops.link")83struct sched_ext_ops select_cpu_vtime_ops = {84 .select_cpu = (void *) select_cpu_vtime_select_cpu,85 .dispatch = (void *) select_cpu_vtime_dispatch,86 .running = (void *) select_cpu_vtime_running,87 .stopping = (void *) select_cpu_vtime_stopping,88 .enable = (void *) select_cpu_vtime_enable,89 .init = (void *) select_cpu_vtime_init,90 .name = "select_cpu_vtime",91 .timeout_ms = 1000U,92};93