90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* A scheduler that validates the behavior of direct dispatching with a default
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* select_cpu implementation, and with the SCX_OPS_ENQ_DFL_NO_DISPATCH ops flag
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* specified.
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*
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* Copyright (c) 2023 Meta Platforms, Inc. and affiliates.
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* Copyright (c) 2023 David Vernet <dvernet@meta.com>
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* Copyright (c) 2023 Tejun Heo <tj@kernel.org>
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*/
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#include <scx/common.bpf.h>
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char _license[] SEC("license") = "GPL";
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bool saw_local = false;
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/* Per-task scheduling context */
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struct task_ctx {
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bool force_local; /* CPU changed by ops.select_cpu() */
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};
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struct {
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__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
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__uint(map_flags, BPF_F_NO_PREALLOC);
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__type(key, int);
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__type(value, struct task_ctx);
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} task_ctx_stor SEC(".maps");
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/* Manually specify the signature until the kfunc is added to the scx repo. */
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s32 scx_bpf_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags,
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bool *found) __ksym;
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s32 BPF_STRUCT_OPS(select_cpu_dfl_nodispatch_select_cpu, struct task_struct *p,
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s32 prev_cpu, u64 wake_flags)
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{
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struct task_ctx *tctx;
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s32 cpu;
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tctx = bpf_task_storage_get(&task_ctx_stor, p, 0, 0);
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if (!tctx) {
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scx_bpf_error("task_ctx lookup failed");
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return -ESRCH;
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}
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cpu = scx_bpf_select_cpu_dfl(p, prev_cpu, wake_flags,
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&tctx->force_local);
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return cpu;
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}
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void BPF_STRUCT_OPS(select_cpu_dfl_nodispatch_enqueue, struct task_struct *p,
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u64 enq_flags)
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{
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u64 dsq_id = SCX_DSQ_GLOBAL;
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struct task_ctx *tctx;
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tctx = bpf_task_storage_get(&task_ctx_stor, p, 0, 0);
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if (!tctx) {
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scx_bpf_error("task_ctx lookup failed");
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return;
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}
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if (tctx->force_local) {
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dsq_id = SCX_DSQ_LOCAL;
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tctx->force_local = false;
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saw_local = true;
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}
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scx_bpf_dispatch(p, dsq_id, SCX_SLICE_DFL, enq_flags);
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}
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s32 BPF_STRUCT_OPS(select_cpu_dfl_nodispatch_init_task,
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struct task_struct *p, struct scx_init_task_args *args)
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{
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if (bpf_task_storage_get(&task_ctx_stor, p, 0,
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BPF_LOCAL_STORAGE_GET_F_CREATE))
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return 0;
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else
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return -ENOMEM;
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}
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SEC(".struct_ops.link")
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struct sched_ext_ops select_cpu_dfl_nodispatch_ops = {
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.select_cpu = (void *) select_cpu_dfl_nodispatch_select_cpu,
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.enqueue = (void *) select_cpu_dfl_nodispatch_enqueue,
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.init_task = (void *) select_cpu_dfl_nodispatch_init_task,
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.name = "select_cpu_dfl_nodispatch",
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};
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