rustu: Import scx_rusty and scx_layered from kernel tree

This commit is contained in:
Tejun Heo 2023-11-30 13:08:36 -10:00
parent 30b40ac4d3
commit 01d8351616
21 changed files with 5442 additions and 1 deletions

1
rust/scx_utils/.gitignore vendored Normal file
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Cargo.lock

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[package] [package]
name = "scx_utils" name = "scx_utils"
version = "0.1.0" version = "0.2.0"
edition = "2021" edition = "2021"
authors = ["Tejun Heo <tj@kernel.org>"] authors = ["Tejun Heo <tj@kernel.org>"]
license = "GPL-2.0" license = "GPL-2.0"

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src/bpf/.output
Cargo.lock
target

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[package]
name = "scx_layered"
version = "0.0.1"
authors = ["Tejun Heo <htejun@meta.com>", "Meta"]
edition = "2021"
description = "Userspace scheduling with BPF for Ads"
license = "GPL-2.0-only"
[dependencies]
anyhow = "1.0"
bitvec = "1.0"
clap = { version = "4.1", features = ["derive", "env", "unicode", "wrap_help"] }
ctrlc = { version = "3.1", features = ["termination"] }
fb_procfs = "0.7"
lazy_static = "1.4"
libbpf-rs = "0.21"
libc = "0.2"
log = "0.4"
scx_utils = { path = "../../../rust/scx_utils", version = "0.2" }
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"
simplelog = "0.12"
[build-dependencies]
scx_utils = { path = "../../../rust/scx_utils", version = "0.2" }
[features]
enable_backtrace = []

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// Copyright (c) Meta Platforms, Inc. and affiliates.
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2.
fn main() {
scx_utils::BpfBuilder::new()
.unwrap()
.enable_intf("src/bpf/intf.h", "bpf_intf.rs")
.enable_skel("src/bpf/main.bpf.c", "bpf")
.build()
.unwrap();
}

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# Get help on options with `rustfmt --help=config`
# Please keep these in alphabetical order.
edition = "2021"
group_imports = "StdExternalCrate"
imports_granularity = "Item"
merge_derives = false
use_field_init_shorthand = true
version = "Two"

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// Copyright (c) Meta Platforms, Inc. and affiliates.
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2.
#ifndef __INTF_H
#define __INTF_H
#include <stdbool.h>
#ifndef __kptr
#ifdef __KERNEL__
#error "__kptr_ref not defined in the kernel"
#endif
#define __kptr
#endif
#ifndef __KERNEL__
typedef unsigned long long u64;
typedef long long s64;
#endif
#include "ravg.bpf.h"
enum consts {
MAX_CPUS_SHIFT = 9,
MAX_CPUS = 1 << MAX_CPUS_SHIFT,
MAX_CPUS_U8 = MAX_CPUS / 8,
MAX_TASKS = 131072,
MAX_PATH = 4096,
MAX_COMM = 16,
MAX_LAYER_MATCH_ORS = 32,
MAX_LAYERS = 16,
USAGE_HALF_LIFE = 100000000, /* 100ms */
/* XXX remove */
MAX_CGRP_PREFIXES = 32
};
/* Statistics */
enum global_stat_idx {
GSTAT_TASK_CTX_FREE_FAILED,
NR_GSTATS,
};
enum layer_stat_idx {
LSTAT_LOCAL,
LSTAT_GLOBAL,
LSTAT_OPEN_IDLE,
LSTAT_AFFN_VIOL,
LSTAT_PREEMPT,
NR_LSTATS,
};
struct cpu_ctx {
bool current_preempt;
u64 layer_cycles[MAX_LAYERS];
u64 gstats[NR_GSTATS];
u64 lstats[MAX_LAYERS][NR_LSTATS];
};
enum layer_match_kind {
MATCH_CGROUP_PREFIX,
MATCH_COMM_PREFIX,
MATCH_NICE_ABOVE,
MATCH_NICE_BELOW,
NR_LAYER_MATCH_KINDS,
};
struct layer_match {
int kind;
char cgroup_prefix[MAX_PATH];
char comm_prefix[MAX_COMM];
int nice_above_or_below;
};
struct layer_match_ands {
struct layer_match matches[NR_LAYER_MATCH_KINDS];
int nr_match_ands;
};
struct layer {
struct layer_match_ands matches[MAX_LAYER_MATCH_ORS];
unsigned int nr_match_ors;
unsigned int idx;
bool open;
bool preempt;
u64 vtime_now;
u64 nr_tasks;
u64 load;
struct ravg_data load_rd;
u64 cpus_seq;
unsigned int refresh_cpus;
unsigned char cpus[MAX_CPUS_U8];
unsigned int nr_cpus; // managed from BPF side
};
#endif /* __INTF_H */

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/* Copyright (c) Meta Platforms, Inc. and affiliates. */
#include "scx_common.bpf.h"
#include "intf.h"
#include <errno.h>
#include <stdbool.h>
#include <string.h>
#include <bpf/bpf_core_read.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
char _license[] SEC("license") = "GPL";
const volatile u32 debug = 0;
const volatile u64 slice_ns = SCX_SLICE_DFL;
const volatile u32 nr_possible_cpus = 1;
const volatile u32 nr_layers = 1;
const volatile bool smt_enabled = true;
const volatile unsigned char all_cpus[MAX_CPUS_U8];
private(all_cpumask) struct bpf_cpumask __kptr *all_cpumask;
struct layer layers[MAX_LAYERS];
u32 fallback_cpu;
static u32 preempt_cursor;
#define dbg(fmt, args...) do { if (debug) bpf_printk(fmt, ##args); } while (0)
#define trace(fmt, args...) do { if (debug > 1) bpf_printk(fmt, ##args); } while (0)
#include "util.bpf.c"
#include "ravg_impl.bpf.h"
struct user_exit_info uei;
static inline bool vtime_before(u64 a, u64 b)
{
return (s64)(a - b) < 0;
}
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__type(key, u32);
__type(value, struct cpu_ctx);
__uint(max_entries, 1);
} cpu_ctxs SEC(".maps");
static struct cpu_ctx *lookup_cpu_ctx(int cpu)
{
struct cpu_ctx *cctx;
u32 zero = 0;
if (cpu < 0)
cctx = bpf_map_lookup_elem(&cpu_ctxs, &zero);
else
cctx = bpf_map_lookup_percpu_elem(&cpu_ctxs, &zero, cpu);
if (!cctx) {
scx_bpf_error("no cpu_ctx for cpu %d", cpu);
return NULL;
}
return cctx;
}
static void gstat_inc(enum global_stat_idx idx, struct cpu_ctx *cctx)
{
if (idx < 0 || idx >= NR_GSTATS) {
scx_bpf_error("invalid global stat idx %d", idx);
return;
}
cctx->gstats[idx]++;
}
static void lstat_inc(enum layer_stat_idx idx, struct layer *layer, struct cpu_ctx *cctx)
{
u64 *vptr;
if ((vptr = MEMBER_VPTR(*cctx, .lstats[layer->idx][idx])))
(*vptr)++;
else
scx_bpf_error("invalid layer or stat idxs: %d, %d", idx, layer->idx);
}
struct lock_wrapper {
struct bpf_spin_lock lock;
};
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, u32);
__type(value, struct lock_wrapper);
__uint(max_entries, MAX_LAYERS);
__uint(map_flags, 0);
} layer_load_locks SEC(".maps");
static void adj_load(u32 layer_idx, s64 adj, u64 now)
{
struct layer *layer;
struct lock_wrapper *lockw;
layer = MEMBER_VPTR(layers, [layer_idx]);
lockw = bpf_map_lookup_elem(&layer_load_locks, &layer_idx);
if (!layer || !lockw) {
scx_bpf_error("Can't access layer%d or its load_lock", layer_idx);
return;
}
bpf_spin_lock(&lockw->lock);
layer->load += adj;
ravg_accumulate(&layer->load_rd, layer->load, now, USAGE_HALF_LIFE);
bpf_spin_unlock(&lockw->lock);
if (debug && adj < 0 && (s64)layer->load < 0)
scx_bpf_error("cpu%d layer%d load underflow (load=%lld adj=%lld)",
bpf_get_smp_processor_id(), layer_idx, layer->load, adj);
}
struct layer_cpumask_wrapper {
struct bpf_cpumask __kptr *cpumask;
};
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, u32);
__type(value, struct layer_cpumask_wrapper);
__uint(max_entries, MAX_LAYERS);
__uint(map_flags, 0);
} layer_cpumasks SEC(".maps");
static struct cpumask *lookup_layer_cpumask(int idx)
{
struct layer_cpumask_wrapper *cpumaskw;
if ((cpumaskw = bpf_map_lookup_elem(&layer_cpumasks, &idx))) {
return (struct cpumask *)cpumaskw->cpumask;
} else {
scx_bpf_error("no layer_cpumask");
return NULL;
}
}
static void refresh_cpumasks(int idx)
{
struct layer_cpumask_wrapper *cpumaskw;
struct layer *layer;
int cpu, total = 0;
if (!__sync_val_compare_and_swap(&layers[idx].refresh_cpus, 1, 0))
return;
cpumaskw = bpf_map_lookup_elem(&layer_cpumasks, &idx);
bpf_for(cpu, 0, nr_possible_cpus) {
u8 *u8_ptr;
if ((u8_ptr = MEMBER_VPTR(layers, [idx].cpus[cpu / 8]))) {
/*
* XXX - The following test should be outside the loop
* but that makes the verifier think that
* cpumaskw->cpumask might be NULL in the loop.
*/
barrier_var(cpumaskw);
if (!cpumaskw || !cpumaskw->cpumask) {
scx_bpf_error("can't happen");
return;
}
if (*u8_ptr & (1 << (cpu % 8))) {
bpf_cpumask_set_cpu(cpu, cpumaskw->cpumask);
total++;
} else {
bpf_cpumask_clear_cpu(cpu, cpumaskw->cpumask);
}
} else {
scx_bpf_error("can't happen");
}
}
// XXX - shouldn't be necessary
layer = MEMBER_VPTR(layers, [idx]);
if (!layer) {
scx_bpf_error("can't happen");
return;
}
layer->nr_cpus = total;
__sync_fetch_and_add(&layer->cpus_seq, 1);
trace("LAYER[%d] now has %d cpus, seq=%llu", idx, layer->nr_cpus, layer->cpus_seq);
}
SEC("fentry/scheduler_tick")
int scheduler_tick_fentry(const void *ctx)
{
int idx;
if (bpf_get_smp_processor_id() == 0)
bpf_for(idx, 0, nr_layers)
refresh_cpumasks(idx);
return 0;
}
struct task_ctx {
int pid;
int layer;
bool refresh_layer;
u64 layer_cpus_seq;
struct bpf_cpumask __kptr *layered_cpumask;
bool all_cpus_allowed;
bool dispatch_local;
u64 started_running_at;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__type(key, pid_t);
__type(value, struct task_ctx);
__uint(max_entries, MAX_TASKS);
__uint(map_flags, 0);
} task_ctxs SEC(".maps");
struct task_ctx *lookup_task_ctx_may_fail(struct task_struct *p)
{
s32 pid = p->pid;
return bpf_map_lookup_elem(&task_ctxs, &pid);
}
struct task_ctx *lookup_task_ctx(struct task_struct *p)
{
struct task_ctx *tctx;
s32 pid = p->pid;
if ((tctx = bpf_map_lookup_elem(&task_ctxs, &pid))) {
return tctx;
} else {
scx_bpf_error("task_ctx lookup failed");
return NULL;
}
}
struct layer *lookup_layer(int idx)
{
if (idx < 0 || idx >= nr_layers) {
scx_bpf_error("invalid layer %d", idx);
return NULL;
}
return &layers[idx];
}
SEC("tp_btf/cgroup_attach_task")
int BPF_PROG(tp_cgroup_attach_task, struct cgroup *cgrp, const char *cgrp_path,
struct task_struct *leader, bool threadgroup)
{
struct task_struct *next;
struct task_ctx *tctx;
int leader_pid = leader->pid;
if (!(tctx = lookup_task_ctx_may_fail(leader)))
return 0;
tctx->refresh_layer = true;
if (!threadgroup)
return 0;
if (!(next = bpf_task_acquire(leader))) {
scx_bpf_error("failed to acquire leader");
return 0;
}
bpf_repeat(MAX_TASKS) {
struct task_struct *p;
int pid;
p = container_of(next->thread_group.next, struct task_struct, thread_group);
bpf_task_release(next);
pid = BPF_CORE_READ(p, pid);
if (pid == leader_pid) {
next = NULL;
break;
}
next = bpf_task_from_pid(pid);
if (!next) {
scx_bpf_error("thread iteration failed");
break;
}
if ((tctx = lookup_task_ctx(next)))
tctx->refresh_layer = true;
}
if (next)
bpf_task_release(next);
return 0;
}
SEC("tp_btf/task_rename")
int BPF_PROG(tp_task_rename, struct task_struct *p, const char *buf)
{
struct task_ctx *tctx;
if ((tctx = lookup_task_ctx_may_fail(p)))
tctx->refresh_layer = true;
return 0;
}
static void maybe_refresh_layered_cpumask(struct cpumask *layered_cpumask,
struct task_struct *p, struct task_ctx *tctx,
const struct cpumask *layer_cpumask)
{
u64 layer_seq = layers->cpus_seq;
if (tctx->layer_cpus_seq == layer_seq)
return;
/*
* XXX - We're assuming that the updated @layer_cpumask matching the new
* @layer_seq is visible which may not be true. For now, leave it as-is.
* Let's update once BPF grows enough memory ordering constructs.
*/
bpf_cpumask_and((struct bpf_cpumask *)layered_cpumask, layer_cpumask, p->cpus_ptr);
tctx->layer_cpus_seq = layer_seq;
trace("%s[%d] cpumask refreshed to seq %llu", p->comm, p->pid, layer_seq);
}
static s32 pick_idle_cpu_from(const struct cpumask *cand_cpumask, s32 prev_cpu,
const struct cpumask *idle_cpumask,
const struct cpumask *idle_smtmask)
{
bool prev_in_cand = bpf_cpumask_test_cpu(prev_cpu, cand_cpumask);
s32 cpu;
/*
* If CPU has SMT, any wholly idle CPU is likely a better pick than
* partially idle @prev_cpu.
*/
if (smt_enabled) {
if (prev_in_cand &&
bpf_cpumask_test_cpu(prev_cpu, idle_smtmask) &&
scx_bpf_test_and_clear_cpu_idle(prev_cpu))
return prev_cpu;
cpu = scx_bpf_pick_idle_cpu(cand_cpumask, SCX_PICK_IDLE_CORE);
if (cpu >= 0)
return cpu;
}
if (prev_in_cand && scx_bpf_test_and_clear_cpu_idle(prev_cpu))
return prev_cpu;
return scx_bpf_pick_idle_cpu(cand_cpumask, 0);
}
s32 BPF_STRUCT_OPS(layered_select_cpu, struct task_struct *p, s32 prev_cpu, u64 wake_flags)
{
const struct cpumask *idle_cpumask, *idle_smtmask;
struct cpumask *layer_cpumask, *layered_cpumask;
struct cpu_ctx *cctx;
struct task_ctx *tctx;
struct layer *layer;
s32 cpu;
/* look up everything we need */
if (!(cctx = lookup_cpu_ctx(-1)) || !(tctx = lookup_task_ctx(p)) ||
!(layered_cpumask = (struct cpumask *)tctx->layered_cpumask))
return prev_cpu;
/*
* We usually update the layer in layered_runnable() to avoid confusing.
* As layered_select_cpu() takes place before runnable, new tasks would
* still have -1 layer. Just return @prev_cpu.
*/
if (tctx->layer < 0)
return prev_cpu;
if (!(layer = lookup_layer(tctx->layer)) ||
!(layer_cpumask = lookup_layer_cpumask(tctx->layer)))
return prev_cpu;
if (!(idle_cpumask = scx_bpf_get_idle_cpumask()))
return prev_cpu;
if (!(idle_smtmask = scx_bpf_get_idle_smtmask())) {
cpu = prev_cpu;
goto out_put_idle_cpumask;
}
/* not much to do if bound to a single CPU */
if (p->nr_cpus_allowed == 1) {
cpu = prev_cpu;
if (scx_bpf_test_and_clear_cpu_idle(prev_cpu)) {
if (!bpf_cpumask_test_cpu(cpu, layer_cpumask))
lstat_inc(LSTAT_AFFN_VIOL, layer, cctx);
goto dispatch_local;
} else {
goto out_put_cpumasks;
}
}
maybe_refresh_layered_cpumask(layered_cpumask, p, tctx, layer_cpumask);
/*
* If CPU has SMT, any wholly idle CPU is likely a better pick than
* partially idle @prev_cpu.
*/
if ((cpu = pick_idle_cpu_from(layered_cpumask, prev_cpu,
idle_cpumask, idle_smtmask)) >= 0)
goto dispatch_local;
/*
* If the layer is an open one, we can try the whole machine.
*/
if (layer->open &&
((cpu = pick_idle_cpu_from(p->cpus_ptr, prev_cpu,
idle_cpumask, idle_smtmask)) >= 0)) {
lstat_inc(LSTAT_OPEN_IDLE, layer, cctx);
goto dispatch_local;
}
cpu = prev_cpu;
goto out_put_cpumasks;
dispatch_local:
tctx->dispatch_local = true;
out_put_cpumasks:
scx_bpf_put_idle_cpumask(idle_smtmask);
out_put_idle_cpumask:
scx_bpf_put_idle_cpumask(idle_cpumask);
return cpu;
}
void BPF_STRUCT_OPS(layered_enqueue, struct task_struct *p, u64 enq_flags)
{
struct cpu_ctx *cctx;
struct task_ctx *tctx;
struct layer *layer;
u64 vtime = p->scx.dsq_vtime;
u32 idx;
if (!(cctx = lookup_cpu_ctx(-1)) || !(tctx = lookup_task_ctx(p)) ||
!(layer = lookup_layer(tctx->layer)))
return;
if (tctx->dispatch_local) {
tctx->dispatch_local = false;
lstat_inc(LSTAT_LOCAL, layer, cctx);
scx_bpf_dispatch(p, SCX_DSQ_LOCAL, slice_ns, enq_flags);
return;
}
lstat_inc(LSTAT_GLOBAL, layer, cctx);
/*
* Limit the amount of budget that an idling task can accumulate
* to one slice.
*/
if (vtime_before(vtime, layer->vtime_now - slice_ns))
vtime = layer->vtime_now - slice_ns;
if (!tctx->all_cpus_allowed) {
lstat_inc(LSTAT_AFFN_VIOL, layer, cctx);
scx_bpf_dispatch(p, SCX_DSQ_GLOBAL, slice_ns, enq_flags);
return;
}
scx_bpf_dispatch_vtime(p, tctx->layer, slice_ns, vtime, enq_flags);
if (!layer->preempt)
return;
bpf_for(idx, 0, nr_possible_cpus) {
struct cpu_ctx *cand_cctx;
u32 cpu = (preempt_cursor + idx) % nr_possible_cpus;
if (!all_cpumask ||
!bpf_cpumask_test_cpu(cpu, (const struct cpumask *)all_cpumask))
continue;
if (!(cand_cctx = lookup_cpu_ctx(cpu)) || cand_cctx->current_preempt)
continue;
scx_bpf_kick_cpu(cpu, SCX_KICK_PREEMPT);
/*
* Round-robining doesn't have to be strict. Let's not bother
* with atomic ops on $preempt_cursor.
*/
preempt_cursor = (cpu + 1) % nr_possible_cpus;
lstat_inc(LSTAT_PREEMPT, layer, cctx);
break;
}
}
void BPF_STRUCT_OPS(layered_dispatch, s32 cpu, struct task_struct *prev)
{
int idx;
/* consume preempting layers first */
bpf_for(idx, 0, nr_layers)
if (layers[idx].preempt && scx_bpf_consume(idx))
return;
/* consume !open layers second */
bpf_for(idx, 0, nr_layers) {
struct layer *layer = &layers[idx];
struct cpumask *layer_cpumask;
if (layer->open)
continue;
/* consume matching layers */
if (!(layer_cpumask = lookup_layer_cpumask(idx)))
return;
if (bpf_cpumask_test_cpu(cpu, layer_cpumask) ||
(cpu == fallback_cpu && layer->nr_cpus == 0)) {
if (scx_bpf_consume(idx))
return;
}
}
/* consume !preempting open layers */
bpf_for(idx, 0, nr_layers) {
if (!layers[idx].preempt && layers[idx].open &&
scx_bpf_consume(idx))
return;
}
}
static bool match_one(struct layer_match *match, struct task_struct *p, const char *cgrp_path)
{
switch (match->kind) {
case MATCH_CGROUP_PREFIX: {
return match_prefix(match->cgroup_prefix, cgrp_path, MAX_PATH);
}
case MATCH_COMM_PREFIX: {
char comm[MAX_COMM];
memcpy(comm, p->comm, MAX_COMM);
return match_prefix(match->comm_prefix, comm, MAX_COMM);
}
case MATCH_NICE_ABOVE:
return (s32)p->static_prio - 120 > match->nice_above_or_below;
case MATCH_NICE_BELOW:
return (s32)p->static_prio - 120 < match->nice_above_or_below;
default:
scx_bpf_error("invalid match kind %d", match->kind);
return false;
}
}
static bool match_layer(struct layer *layer, struct task_struct *p, const char *cgrp_path)
{
u32 nr_match_ors = layer->nr_match_ors;
u64 or_idx, and_idx;
if (nr_match_ors > MAX_LAYER_MATCH_ORS) {
scx_bpf_error("too many ORs");
return false;
}
bpf_for(or_idx, 0, nr_match_ors) {
struct layer_match_ands *ands;
bool matched = true;
barrier_var(or_idx);
if (or_idx >= MAX_LAYER_MATCH_ORS)
return false; /* can't happen */
ands = &layer->matches[or_idx];
if (ands->nr_match_ands > NR_LAYER_MATCH_KINDS) {
scx_bpf_error("too many ANDs");
return false;
}
bpf_for(and_idx, 0, ands->nr_match_ands) {
struct layer_match *match;
barrier_var(and_idx);
if (and_idx >= NR_LAYER_MATCH_KINDS)
return false; /* can't happen */
match = &ands->matches[and_idx];
if (!match_one(match, p, cgrp_path)) {
matched = false;
break;
}
}
if (matched)
return true;
}
return false;
}
static void maybe_refresh_layer(struct task_struct *p, struct task_ctx *tctx)
{
const char *cgrp_path;
bool matched = false;
u64 idx; // XXX - int makes verifier unhappy
if (!tctx->refresh_layer)
return;
tctx->refresh_layer = false;
if (!(cgrp_path = format_cgrp_path(p->cgroups->dfl_cgrp)))
return;
if (tctx->layer >= 0 && tctx->layer < nr_layers)
__sync_fetch_and_add(&layers[tctx->layer].nr_tasks, -1);
bpf_for(idx, 0, nr_layers) {
if (match_layer(&layers[idx], p, cgrp_path)) {
matched = true;
break;
}
}
if (matched) {
struct layer *layer = &layers[idx];
tctx->layer = idx;
tctx->layer_cpus_seq = layer->cpus_seq - 1;
__sync_fetch_and_add(&layer->nr_tasks, 1);
/*
* XXX - To be correct, we'd need to calculate the vtime
* delta in the previous layer, scale it by the load
* fraction difference and then offset from the new
* layer's vtime_now. For now, just do the simple thing
* and assume the offset to be zero.
*
* Revisit if high frequency dynamic layer switching
* needs to be supported.
*/
p->scx.dsq_vtime = layer->vtime_now;
} else {
scx_bpf_error("[%s]%d didn't match any layer", p->comm, p->pid);
}
if (tctx->layer < nr_layers - 1)
trace("LAYER=%d %s[%d] cgrp=\"%s\"",
tctx->layer, p->comm, p->pid, cgrp_path);
}
void BPF_STRUCT_OPS(layered_runnable, struct task_struct *p, u64 enq_flags)
{
u64 now = bpf_ktime_get_ns();
struct task_ctx *tctx;
if (!(tctx = lookup_task_ctx(p)))
return;
maybe_refresh_layer(p, tctx);
adj_load(tctx->layer, p->scx.weight, now);
}
void BPF_STRUCT_OPS(layered_running, struct task_struct *p)
{
struct cpu_ctx *cctx;
struct task_ctx *tctx;
struct layer *layer;
if (!(cctx = lookup_cpu_ctx(-1)) || !(tctx = lookup_task_ctx(p)) ||
!(layer = lookup_layer(tctx->layer)))
return;
if (vtime_before(layer->vtime_now, p->scx.dsq_vtime))
layer->vtime_now = p->scx.dsq_vtime;
cctx->current_preempt = layer->preempt;
tctx->started_running_at = bpf_ktime_get_ns();
}
void BPF_STRUCT_OPS(layered_stopping, struct task_struct *p, bool runnable)
{
struct cpu_ctx *cctx;
struct task_ctx *tctx;
u64 used;
u32 layer;
if (!(cctx = lookup_cpu_ctx(-1)) || !(tctx = lookup_task_ctx(p)))
return;
layer = tctx->layer;
if (layer >= nr_layers) {
scx_bpf_error("invalid layer %u", layer);
return;
}
used = bpf_ktime_get_ns() - tctx->started_running_at;
cctx->layer_cycles[layer] += used;
cctx->current_preempt = false;
/* scale the execution time by the inverse of the weight and charge */
p->scx.dsq_vtime += used * 100 / p->scx.weight;
}
void BPF_STRUCT_OPS(layered_quiescent, struct task_struct *p, u64 deq_flags)
{
struct task_ctx *tctx;
if ((tctx = lookup_task_ctx(p)))
adj_load(tctx->layer, -(s64)p->scx.weight, bpf_ktime_get_ns());
}
void BPF_STRUCT_OPS(layered_set_weight, struct task_struct *p, u32 weight)
{
struct task_ctx *tctx;
if ((tctx = lookup_task_ctx(p)))
tctx->refresh_layer = true;
}
void BPF_STRUCT_OPS(layered_set_cpumask, struct task_struct *p,
const struct cpumask *cpumask)
{
struct task_ctx *tctx;
if (!(tctx = lookup_task_ctx(p)))
return;
if (!all_cpumask) {
scx_bpf_error("NULL all_cpumask");
return;
}
tctx->all_cpus_allowed =
bpf_cpumask_subset((const struct cpumask *)all_cpumask, cpumask);
}
s32 BPF_STRUCT_OPS(layered_prep_enable, struct task_struct *p,
struct scx_enable_args *args)
{
struct task_ctx tctx_init = {
.pid = p->pid,
.layer = -1,
.refresh_layer = true,
};
struct task_ctx *tctx;
struct bpf_cpumask *cpumask;
s32 pid = p->pid;
s32 ret;
if (all_cpumask)
tctx_init.all_cpus_allowed =
bpf_cpumask_subset((const struct cpumask *)all_cpumask, p->cpus_ptr);
else
scx_bpf_error("missing all_cpumask");
/*
* XXX - We want BPF_NOEXIST but bpf_map_delete_elem() in .disable() may
* fail spuriously due to BPF recursion protection triggering
* unnecessarily.
*/
if ((ret = bpf_map_update_elem(&task_ctxs, &pid, &tctx_init, 0 /*BPF_NOEXIST*/))) {
scx_bpf_error("task_ctx allocation failure, ret=%d", ret);
return ret;
}
/*
* Read the entry from the map immediately so we can add the cpumask
* with bpf_kptr_xchg().
*/
if (!(tctx = lookup_task_ctx(p)))
return -ENOENT;
cpumask = bpf_cpumask_create();
if (!cpumask) {
bpf_map_delete_elem(&task_ctxs, &pid);
return -ENOMEM;
}
cpumask = bpf_kptr_xchg(&tctx->layered_cpumask, cpumask);
if (cpumask) {
/* Should never happen as we just inserted it above. */
bpf_cpumask_release(cpumask);
bpf_map_delete_elem(&task_ctxs, &pid);
return -EINVAL;
}
/*
* We are matching cgroup hierarchy path directly rather than the CPU
* controller path. As the former isn't available during the scheduler
* fork path, let's delay the layer selection until the first
* runnable().
*/
return 0;
}
void BPF_STRUCT_OPS(layered_cancel_enable, struct task_struct *p)
{
s32 pid = p->pid;
bpf_map_delete_elem(&task_ctxs, &pid);
}
void BPF_STRUCT_OPS(layered_disable, struct task_struct *p)
{
struct cpu_ctx *cctx;
struct task_ctx *tctx;
s32 pid = p->pid;
int ret;
if (!(cctx = lookup_cpu_ctx(-1)) || !(tctx = lookup_task_ctx(p)))
return;
if (tctx->layer >= 0 && tctx->layer < nr_layers)
__sync_fetch_and_add(&layers[tctx->layer].nr_tasks, -1);
/*
* XXX - There's no reason delete should fail here but BPF's recursion
* protection can unnecessarily fail the operation. The fact that
* deletions aren't reliable means that we sometimes leak task_ctx and
* can't use BPF_NOEXIST on allocation in .prep_enable().
*/
ret = bpf_map_delete_elem(&task_ctxs, &pid);
if (ret)
gstat_inc(GSTAT_TASK_CTX_FREE_FAILED, cctx);
}
s32 BPF_STRUCT_OPS_SLEEPABLE(layered_init)
{
struct bpf_cpumask *cpumask;
int i, j, k, nr_online_cpus, ret;
scx_bpf_switch_all();
cpumask = bpf_cpumask_create();
if (!cpumask)
return -ENOMEM;
nr_online_cpus = 0;
bpf_for(i, 0, nr_possible_cpus) {
const volatile u8 *u8_ptr;
if ((u8_ptr = MEMBER_VPTR(all_cpus, [i / 8]))) {
if (*u8_ptr & (1 << (i % 8))) {
bpf_cpumask_set_cpu(i, cpumask);
nr_online_cpus++;
}
} else {
return -EINVAL;
}
}
cpumask = bpf_kptr_xchg(&all_cpumask, cpumask);
if (cpumask)
bpf_cpumask_release(cpumask);
dbg("CFG: Dumping configuration, nr_online_cpus=%d smt_enabled=%d",
nr_online_cpus, smt_enabled);
bpf_for(i, 0, nr_layers) {
struct layer *layer = &layers[i];
dbg("CFG LAYER[%d] open=%d preempt=%d",
i, layer->open, layer->preempt);
if (layer->nr_match_ors > MAX_LAYER_MATCH_ORS) {
scx_bpf_error("too many ORs");
return -EINVAL;
}
bpf_for(j, 0, layer->nr_match_ors) {
struct layer_match_ands *ands = MEMBER_VPTR(layers, [i].matches[j]);
if (!ands) {
scx_bpf_error("shouldn't happen");
return -EINVAL;
}
if (ands->nr_match_ands > NR_LAYER_MATCH_KINDS) {
scx_bpf_error("too many ANDs");
return -EINVAL;
}
dbg("CFG OR[%02d]", j);
bpf_for(k, 0, ands->nr_match_ands) {
char header[32];
u64 header_data[1] = { k };
struct layer_match *match;
bpf_snprintf(header, sizeof(header), "CFG AND[%02d]:",
header_data, sizeof(header_data));
match = MEMBER_VPTR(layers, [i].matches[j].matches[k]);
if (!match) {
scx_bpf_error("shouldn't happen");
return -EINVAL;
}
switch (match->kind) {
case MATCH_CGROUP_PREFIX:
dbg("%s CGROUP_PREFIX \"%s\"", header, match->cgroup_prefix);
break;
case MATCH_COMM_PREFIX:
dbg("%s COMM_PREFIX \"%s\"", header, match->comm_prefix);
break;
case MATCH_NICE_ABOVE:
dbg("%s NICE_ABOVE %d", header, match->nice_above_or_below);
break;
case MATCH_NICE_BELOW:
dbg("%s NICE_BELOW %d", header, match->nice_above_or_below);
break;
default:
scx_bpf_error("%s Invalid kind", header);
return -EINVAL;
}
}
if (ands->nr_match_ands == 0)
dbg("CFG DEFAULT");
}
}
bpf_for(i, 0, nr_layers) {
struct layer_cpumask_wrapper *cpumaskw;
layers[i].idx = i;
ret = scx_bpf_create_dsq(i, -1);
if (ret < 0)
return ret;
if (!(cpumaskw = bpf_map_lookup_elem(&layer_cpumasks, &i)))
return -ENONET;
cpumask = bpf_cpumask_create();
if (!cpumask)
return -ENOMEM;
/*
* Start all layers with full cpumask so that everything runs
* everywhere. This will soon be updated by refresh_cpumasks()
* once the scheduler starts running.
*/
bpf_cpumask_setall(cpumask);
cpumask = bpf_kptr_xchg(&cpumaskw->cpumask, cpumask);
if (cpumask)
bpf_cpumask_release(cpumask);
}
return 0;
}
void BPF_STRUCT_OPS(layered_exit, struct scx_exit_info *ei)
{
uei_record(&uei, ei);
}
SEC(".struct_ops.link")
struct sched_ext_ops layered = {
.select_cpu = (void *)layered_select_cpu,
.enqueue = (void *)layered_enqueue,
.dispatch = (void *)layered_dispatch,
.runnable = (void *)layered_runnable,
.running = (void *)layered_running,
.stopping = (void *)layered_stopping,
.quiescent = (void *)layered_quiescent,
.set_weight = (void *)layered_set_weight,
.set_cpumask = (void *)layered_set_cpumask,
.prep_enable = (void *)layered_prep_enable,
.cancel_enable = (void *)layered_cancel_enable,
.disable = (void *)layered_disable,
.init = (void *)layered_init,
.exit = (void *)layered_exit,
.name = "layered",
};

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/* to be included in the main bpf.c file */
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
__uint(key_size, sizeof(u32));
/* double size because verifier can't follow length calculation */
__uint(value_size, 2 * MAX_PATH);
__uint(max_entries, 1);
} cgrp_path_bufs SEC(".maps");
static char *format_cgrp_path(struct cgroup *cgrp)
{
u32 zero = 0;
char *path = bpf_map_lookup_elem(&cgrp_path_bufs, &zero);
u32 len = 0, level, max_level;
if (!path) {
scx_bpf_error("cgrp_path_buf lookup failed");
return NULL;
}
max_level = cgrp->level;
if (max_level > 127)
max_level = 127;
bpf_for(level, 1, max_level + 1) {
int ret;
if (level > 1 && len < MAX_PATH - 1)
path[len++] = '/';
if (len >= MAX_PATH - 1) {
scx_bpf_error("cgrp_path_buf overflow");
return NULL;
}
ret = bpf_probe_read_kernel_str(path + len, MAX_PATH - len - 1,
BPF_CORE_READ(cgrp, ancestors[level], kn, name));
if (ret < 0) {
scx_bpf_error("bpf_probe_read_kernel_str failed");
return NULL;
}
len += ret - 1;
}
if (len >= MAX_PATH - 2) {
scx_bpf_error("cgrp_path_buf overflow");
return NULL;
}
path[len] = '/';
path[len + 1] = '\0';
return path;
}
static inline bool match_prefix(const char *prefix, const char *str, u32 max_len)
{
int c;
bpf_for(c, 0, max_len) {
if (prefix[c] == '\0')
return true;
if (str[c] != prefix[c])
return false;
}
return false;
}

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// Copyright (c) Meta Platforms, Inc. and affiliates.
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2.
#![allow(non_upper_case_globals)]
#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
#![allow(dead_code)]
include!(concat!(env!("OUT_DIR"), "/bpf_intf.rs"));

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// Copyright (c) Meta Platforms, Inc. and affiliates.
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2.
// We can't directly include the generated skeleton in main.rs as it may
// contain compiler attributes that can't be `include!()`ed via macro and we
// can't use the `#[path = "..."]` because `concat!(env!("OUT_DIR"),
// "/bpf.skel.rs")` does not work inside the path attribute yet (see
// https://github.com/rust-lang/rust/pull/83366).
include!(concat!(env!("OUT_DIR"), "/bpf_skel.rs"));

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3
scheds/rust-user/scx_rusty/.gitignore vendored Normal file
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src/bpf/.output
Cargo.lock
target

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[package]
name = "scx_rusty"
version = "0.5.0"
authors = ["Dan Schatzberg <dschatzberg@meta.com>", "Meta"]
edition = "2021"
description = "Userspace scheduling with BPF"
license = "GPL-2.0-only"
[dependencies]
anyhow = "1.0.65"
bitvec = { version = "1.0", features = ["serde"] }
clap = { version = "4.1", features = ["derive", "env", "unicode", "wrap_help"] }
ctrlc = { version = "3.1", features = ["termination"] }
fb_procfs = "0.7.0"
hex = "0.4.3"
libbpf-rs = "0.21.0"
libc = "0.2.137"
log = "0.4.17"
ordered-float = "3.4.0"
scx_utils = { path = "../../../rust/scx_utils", version = "0.2" }
simplelog = "0.12.0"
[build-dependencies]
scx_utils = { path = "../../../rust/scx_utils", version = "0.2" }
[features]
enable_backtrace = []

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// Copyright (c) Meta Platforms, Inc. and affiliates.
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2.
fn main() {
scx_utils::BpfBuilder::new()
.unwrap()
.enable_intf("src/bpf/intf.h", "bpf_intf.rs")
.enable_skel("src/bpf/main.bpf.c", "bpf")
.build()
.unwrap();
}

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# Get help on options with `rustfmt --help=config`
# Please keep these in alphabetical order.
edition = "2021"
group_imports = "StdExternalCrate"
imports_granularity = "Item"
merge_derives = false
use_field_init_shorthand = true
version = "Two"

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// Copyright (c) Meta Platforms, Inc. and affiliates.
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2.
#ifndef __INTF_H
#define __INTF_H
#include <stdbool.h>
#ifndef __kptr
#ifdef __KERNEL__
#error "__kptr_ref not defined in the kernel"
#endif
#define __kptr
#endif
#ifndef __KERNEL__
typedef unsigned char u8;
typedef unsigned int u32;
typedef unsigned long long u64;
#endif
#include "ravg.bpf.h"
enum consts {
MAX_CPUS = 512,
MAX_DOMS = 64, /* limited to avoid complex bitmask ops */
CACHELINE_SIZE = 64,
/*
* When userspace load balancer is trying to determine the tasks to push
* out from an overloaded domain, it looks at the the following number
* of recently active tasks of the domain. While this may lead to
* spurious migration victim selection failures in pathological cases,
* this isn't a practical problem as the LB rounds are best-effort
* anyway and will be retried until loads are balanced.
*/
MAX_DOM_ACTIVE_PIDS = 1024,
};
/* Statistics */
enum stat_idx {
/* The following fields add up to all dispatched tasks */
RUSTY_STAT_WAKE_SYNC,
RUSTY_STAT_PREV_IDLE,
RUSTY_STAT_GREEDY_IDLE,
RUSTY_STAT_PINNED,
RUSTY_STAT_DIRECT_DISPATCH,
RUSTY_STAT_DIRECT_GREEDY,
RUSTY_STAT_DIRECT_GREEDY_FAR,
RUSTY_STAT_DSQ_DISPATCH,
RUSTY_STAT_GREEDY,
/* Extra stats that don't contribute to total */
RUSTY_STAT_REPATRIATE,
RUSTY_STAT_KICK_GREEDY,
RUSTY_STAT_LOAD_BALANCE,
/* Errors */
RUSTY_STAT_TASK_GET_ERR,
RUSTY_NR_STATS,
};
struct task_ctx {
/* The domains this task can run on */
u64 dom_mask;
struct bpf_cpumask __kptr *cpumask;
u32 dom_id;
u32 weight;
bool runnable;
u64 dom_active_pids_gen;
u64 running_at;
/* The task is a workqueue worker thread */
bool is_kworker;
/* Allowed on all CPUs and eligible for DIRECT_GREEDY optimization */
bool all_cpus;
/* select_cpu() telling enqueue() to queue directly on the DSQ */
bool dispatch_local;
struct ravg_data dcyc_rd;
};
struct dom_ctx {
u64 vtime_now;
struct bpf_cpumask __kptr *cpumask;
struct bpf_cpumask __kptr *direct_greedy_cpumask;
u64 load;
struct ravg_data load_rd;
u64 dbg_load_printed_at;
};
#endif /* __INTF_H */

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// Copyright (c) Meta Platforms, Inc. and affiliates.
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2.
#![allow(non_upper_case_globals)]
#![allow(non_camel_case_types)]
#![allow(non_snake_case)]
#![allow(dead_code)]
include!(concat!(env!("OUT_DIR"), "/bpf_intf.rs"));

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// Copyright (c) Meta Platforms, Inc. and affiliates.
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2.
// We can't directly include the generated skeleton in main.rs as it may
// contain compiler attributes that can't be `include!()`ed via macro and we
// can't use the `#[path = "..."]` because `concat!(env!("OUT_DIR"),
// "/bpf.skel.rs")` does not work inside the path attribute yet (see
// https://github.com/rust-lang/rust/pull/83366).
include!(concat!(env!("OUT_DIR"), "/bpf_skel.rs"));

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