diff --git a/tools/sched_ext/.gitignore b/tools/sched_ext/.gitignore
new file mode 100644
index 000000000000..6734f7fd9324
--- /dev/null
+++ b/tools/sched_ext/.gitignore
@@ -0,0 +1,5 @@
+scx_example_dummy
+scx_example_qmap
+*.skel.h
+*.subskel.h
+/tools/
diff --git a/tools/sched_ext/Makefile b/tools/sched_ext/Makefile
new file mode 100644
index 000000000000..926b0a36c221
--- /dev/null
+++ b/tools/sched_ext/Makefile
@@ -0,0 +1,188 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
+include ../build/Build.include
+include ../scripts/Makefile.arch
+include ../scripts/Makefile.include
+
+ifneq ($(LLVM),)
+ifneq ($(filter %/,$(LLVM)),)
+LLVM_PREFIX := $(LLVM)
+else ifneq ($(filter -%,$(LLVM)),)
+LLVM_SUFFIX := $(LLVM)
+endif
+
+CLANG_TARGET_FLAGS_arm          := arm-linux-gnueabi
+CLANG_TARGET_FLAGS_arm64        := aarch64-linux-gnu
+CLANG_TARGET_FLAGS_hexagon      := hexagon-linux-musl
+CLANG_TARGET_FLAGS_m68k         := m68k-linux-gnu
+CLANG_TARGET_FLAGS_mips         := mipsel-linux-gnu
+CLANG_TARGET_FLAGS_powerpc      := powerpc64le-linux-gnu
+CLANG_TARGET_FLAGS_riscv        := riscv64-linux-gnu
+CLANG_TARGET_FLAGS_s390         := s390x-linux-gnu
+CLANG_TARGET_FLAGS_x86          := x86_64-linux-gnu
+CLANG_TARGET_FLAGS              := $(CLANG_TARGET_FLAGS_$(ARCH))
+
+ifeq ($(CROSS_COMPILE),)
+ifeq ($(CLANG_TARGET_FLAGS),)
+$(error Specify CROSS_COMPILE or add '--target=' option to lib.mk
+else
+CLANG_FLAGS     += --target=$(CLANG_TARGET_FLAGS)
+endif # CLANG_TARGET_FLAGS
+else
+CLANG_FLAGS     += --target=$(notdir $(CROSS_COMPILE:%-=%))
+endif # CROSS_COMPILE
+
+CC := $(LLVM_PREFIX)clang$(LLVM_SUFFIX) $(CLANG_FLAGS) -fintegrated-as
+else
+CC := $(CROSS_COMPILE)gcc
+endif # LLVM
+
+CURDIR := $(abspath .)
+TOOLSDIR := $(abspath ..)
+LIBDIR := $(TOOLSDIR)/lib
+BPFDIR := $(LIBDIR)/bpf
+TOOLSINCDIR := $(TOOLSDIR)/include
+BPFTOOLDIR := $(TOOLSDIR)/bpf/bpftool
+APIDIR := $(TOOLSINCDIR)/uapi
+GENDIR := $(abspath ../../include/generated)
+GENHDR := $(GENDIR)/autoconf.h
+
+SCRATCH_DIR := $(CURDIR)/tools
+BUILD_DIR := $(SCRATCH_DIR)/build
+INCLUDE_DIR := $(SCRATCH_DIR)/include
+BPFOBJ_DIR := $(BUILD_DIR)/libbpf
+BPFOBJ := $(BPFOBJ_DIR)/libbpf.a
+ifneq ($(CROSS_COMPILE),)
+HOST_BUILD_DIR		:= $(BUILD_DIR)/host
+HOST_SCRATCH_DIR	:= host-tools
+HOST_INCLUDE_DIR	:= $(HOST_SCRATCH_DIR)/include
+else
+HOST_BUILD_DIR		:= $(BUILD_DIR)
+HOST_SCRATCH_DIR	:= $(SCRATCH_DIR)
+HOST_INCLUDE_DIR	:= $(INCLUDE_DIR)
+endif
+HOST_BPFOBJ := $(HOST_BUILD_DIR)/libbpf/libbpf.a
+RESOLVE_BTFIDS := $(HOST_BUILD_DIR)/resolve_btfids/resolve_btfids
+DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool
+
+VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux)					\
+		     $(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux)		\
+		     ../../vmlinux						\
+		     /sys/kernel/btf/vmlinux					\
+		     /boot/vmlinux-$(shell uname -r)
+VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
+ifeq ($(VMLINUX_BTF),)
+$(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)")
+endif
+
+BPFTOOL ?= $(DEFAULT_BPFTOOL)
+
+ifneq ($(wildcard $(GENHDR)),)
+  GENFLAGS := -DHAVE_GENHDR
+endif
+
+CFLAGS += -g -O2 -rdynamic -pthread -Wall -Werror $(GENFLAGS)			\
+	  -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR)				\
+	  -I$(TOOLSINCDIR) -I$(APIDIR)
+
+# Silence some warnings when compiled with clang
+ifneq ($(LLVM),)
+CFLAGS += -Wno-unused-command-line-argument
+endif
+
+LDFLAGS = -lelf -lz -lpthread
+
+IS_LITTLE_ENDIAN = $(shell $(CC) -dM -E - </dev/null |				\
+			grep 'define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__')
+
+# Get Clang's default includes on this system, as opposed to those seen by
+# '-target bpf'. This fixes "missing" files on some architectures/distros,
+# such as asm/byteorder.h, asm/socket.h, asm/sockios.h, sys/cdefs.h etc.
+#
+# Use '-idirafter': Don't interfere with include mechanics except where the
+# build would have failed anyways.
+define get_sys_includes
+$(shell $(1) -v -E - </dev/null 2>&1 \
+	| sed -n '/<...> search starts here:/,/End of search list./{ s| \(/.*\)|-idirafter \1|p }') \
+$(shell $(1) -dM -E - </dev/null | grep '__riscv_xlen ' | awk '{printf("-D__riscv_xlen=%d -D__BITS_PER_LONG=%d", $$3, $$3)}')
+endef
+
+BPF_CFLAGS = -g -D__TARGET_ARCH_$(SRCARCH)					\
+	     $(if $(IS_LITTLE_ENDIAN),-mlittle-endian,-mbig-endian)		\
+	     -I$(INCLUDE_DIR) -I$(CURDIR) -I$(APIDIR)				\
+	     -I../../include							\
+	     $(call get_sys_includes,$(CLANG))					\
+	     -Wno-compare-distinct-pointer-types				\
+	     -O2 -mcpu=v3
+
+all: scx_example_dummy scx_example_qmap
+
+# sort removes libbpf duplicates when not cross-building
+MAKE_DIRS := $(sort $(BUILD_DIR)/libbpf $(HOST_BUILD_DIR)/libbpf		\
+	       $(HOST_BUILD_DIR)/bpftool $(HOST_BUILD_DIR)/resolve_btfids	\
+	       $(INCLUDE_DIR))
+
+$(MAKE_DIRS):
+	$(call msg,MKDIR,,$@)
+	$(Q)mkdir -p $@
+
+$(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)			\
+	   $(APIDIR)/linux/bpf.h						\
+	   | $(BUILD_DIR)/libbpf
+	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/	\
+		    EXTRA_CFLAGS='-g -O0 -fPIC'					\
+		    DESTDIR=$(SCRATCH_DIR) prefix= all install_headers
+
+$(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)	\
+		    $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/bpftool
+	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)				\
+		    ARCH= CROSS_COMPILE= CC=$(HOSTCC) LD=$(HOSTLD)		\
+		    EXTRA_CFLAGS='-g -O0'					\
+		    OUTPUT=$(HOST_BUILD_DIR)/bpftool/				\
+		    LIBBPF_OUTPUT=$(HOST_BUILD_DIR)/libbpf/			\
+		    LIBBPF_DESTDIR=$(HOST_SCRATCH_DIR)/				\
+		    prefix= DESTDIR=$(HOST_SCRATCH_DIR)/ install-bin
+
+$(INCLUDE_DIR)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) | $(INCLUDE_DIR)
+ifeq ($(VMLINUX_H),)
+	$(call msg,GEN,,$@)
+	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
+else
+	$(call msg,CP,,$@)
+	$(Q)cp "$(VMLINUX_H)" $@
+endif
+
+%.bpf.o: %.bpf.c $(INCLUDE_DIR)/vmlinux.h scx_common.bpf.h user_exit_info.h	\
+	| $(BPFOBJ)
+	$(call msg,CLNG-BPF,,$@)
+	$(Q)$(CLANG) $(BPF_CFLAGS) -target bpf -c $< -o $@
+
+%.skel.h: %.bpf.o $(BPFTOOL)
+	$(call msg,GEN-SKEL,,$@)
+	$(Q)$(BPFTOOL) gen object $(<:.o=.linked1.o) $<
+	$(Q)$(BPFTOOL) gen object $(<:.o=.linked2.o) $(<:.o=.linked1.o)
+	$(Q)$(BPFTOOL) gen object $(<:.o=.linked3.o) $(<:.o=.linked2.o)
+	$(Q)diff $(<:.o=.linked2.o) $(<:.o=.linked3.o)
+	$(Q)$(BPFTOOL) gen skeleton $(<:.o=.linked3.o) name $(<:.bpf.o=) > $@
+	$(Q)$(BPFTOOL) gen subskeleton $(<:.o=.linked3.o) name $(<:.bpf.o=) > $(@:.skel.h=.subskel.h)
+
+scx_example_dummy: scx_example_dummy.c scx_example_dummy.skel.h user_exit_info.h
+	$(CC) $(CFLAGS) -c $< -o $@.o
+	$(CC) -o $@ $@.o $(HOST_BPFOBJ) $(LDFLAGS)
+
+scx_example_qmap: scx_example_qmap.c scx_example_qmap.skel.h user_exit_info.h
+	$(CC) $(CFLAGS) -c $< -o $@.o
+	$(CC) -o $@ $@.o $(HOST_BPFOBJ) $(LDFLAGS)
+
+clean:
+	rm -rf $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)
+	rm -f *.o *.bpf.o *.skel.h *.subskel.h
+	rm -f scx_example_dummy scx_example_qmap
+
+.PHONY: all clean
+
+# delete failed targets
+.DELETE_ON_ERROR:
+
+# keep intermediate (.skel.h, .bpf.o, etc) targets
+.SECONDARY:
diff --git a/tools/sched_ext/gnu/stubs.h b/tools/sched_ext/gnu/stubs.h
new file mode 100644
index 000000000000..719225b16626
--- /dev/null
+++ b/tools/sched_ext/gnu/stubs.h
@@ -0,0 +1 @@
+/* dummy .h to trick /usr/include/features.h to work with 'clang -target bpf' */
diff --git a/tools/sched_ext/scx_common.bpf.h b/tools/sched_ext/scx_common.bpf.h
new file mode 100644
index 000000000000..b40a4fc6a159
--- /dev/null
+++ b/tools/sched_ext/scx_common.bpf.h
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2022 Tejun Heo <tj@kernel.org>
+ * Copyright (c) 2022 David Vernet <dvernet@meta.com>
+ */
+#ifndef __SCHED_EXT_COMMON_BPF_H
+#define __SCHED_EXT_COMMON_BPF_H
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <linux/errno.h>
+#include "user_exit_info.h"
+
+/*
+ * Earlier versions of clang/pahole lost upper 32bits in 64bit enums which can
+ * lead to really confusing misbehaviors. Let's trigger a build failure.
+ */
+static inline void ___vmlinux_h_sanity_check___(void)
+{
+	_Static_assert(SCX_DSQ_FLAG_BUILTIN,
+		       "bpftool generated vmlinux.h is missing high bits for 64bit enums, upgrade clang and pahole");
+}
+
+void scx_bpf_error_bstr(char *fmt, unsigned long long *data, u32 data_len) __ksym;
+
+static inline __attribute__((format(printf, 1, 2)))
+void ___scx_bpf_error_format_checker(const char *fmt, ...) {}
+
+/*
+ * scx_bpf_error() wraps the scx_bpf_error_bstr() kfunc with variadic arguments
+ * instead of an array of u64. Note that __param[] must have at least one
+ * element to keep the verifier happy.
+ */
+#define scx_bpf_error(fmt, args...)						\
+({										\
+	static char ___fmt[] = fmt;						\
+	unsigned long long ___param[___bpf_narg(args) ?: 1] = {};		\
+										\
+	_Pragma("GCC diagnostic push")						\
+	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")			\
+	___bpf_fill(___param, args);						\
+	_Pragma("GCC diagnostic pop")						\
+										\
+	scx_bpf_error_bstr(___fmt, ___param, sizeof(___param));			\
+										\
+	___scx_bpf_error_format_checker(fmt, ##args);				\
+})
+
+/* BPF core task / cgroup kfunc helpers */
+struct task_struct *bpf_task_from_pid(s32 pid) __ksym;
+struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
+void bpf_task_release(struct task_struct *p) __ksym;
+
+/* BPF core cpumask kfuncs */
+struct bpf_cpumask *bpf_cpumask_create(void) __ksym;
+struct bpf_cpumask *bpf_cpumask_acquire(struct bpf_cpumask *cpumask) __ksym;
+struct bpf_cpumask *bpf_cpumask_kptr_get(struct bpf_cpumask **map_value) __ksym;
+void bpf_cpumask_release(struct bpf_cpumask *cpumask) __ksym;
+bool bpf_cpumask_test_cpu(u32 cpu, const struct cpumask *cpumask) __ksym;
+void bpf_cpumask_set_cpu(u32 cpu, struct bpf_cpumask *cpumask) __ksym;
+void bpf_cpumask_clear_cpu(u32 cpu, struct bpf_cpumask *cpumask) __ksym;
+void bpf_cpumask_copy(struct bpf_cpumask *dst, const struct cpumask *src) __ksym;
+bool bpf_cpumask_and(struct bpf_cpumask *dst, const struct cpumask *src1,
+		     const struct cpumask *src2) __ksym;
+u32 bpf_cpumask_first(const struct cpumask *cpumask) __ksym;
+
+s32 scx_bpf_create_dsq(u64 dsq_id, s32 node) __ksym;
+bool scx_bpf_consume(u64 dsq_id) __ksym;
+u32 scx_bpf_dispatch_nr_slots(void) __ksym;
+void scx_bpf_dispatch(struct task_struct *p, u64 dsq_id, u64 slice, u64 enq_flags) __ksym;
+s32 scx_bpf_dsq_nr_queued(u64 dsq_id) __ksym;
+bool scx_bpf_test_and_clear_cpu_idle(s32 cpu) __ksym;
+s32 scx_bpf_pick_idle_cpu(const cpumask_t *cpus_allowed) __ksym;
+const struct cpumask *scx_bpf_get_idle_percpu_cpumask(void) __ksym;
+const struct cpumask *scx_bpf_get_idle_smt_cpumask(void) __ksym;
+void scx_bpf_put_idle_cpumask(const struct cpumask *cpumask) __ksym;
+void scx_bpf_destroy_dsq(u64 dsq_id) __ksym;
+bool scx_bpf_task_running(const struct task_struct *p) __ksym;
+s32 scx_bpf_task_cpu(const struct task_struct *p) __ksym;
+
+#define PF_KTHREAD			0x00200000	/* I am a kernel thread */
+#define PF_EXITING			0x00000004
+#define CLOCK_MONOTONIC			1
+
+#define BPF_STRUCT_OPS(name, args...)						\
+SEC("struct_ops/"#name)								\
+BPF_PROG(name, ##args)
+
+#define BPF_STRUCT_OPS_SLEEPABLE(name, args...)					\
+SEC("struct_ops.s/"#name)							\
+BPF_PROG(name, ##args)
+
+/**
+ * MEMBER_VPTR - Obtain the verified pointer to a struct or array member
+ * @base: struct or array to index
+ * @member: dereferenced member (e.g. ->field, [idx0][idx1], ...)
+ *
+ * The verifier often gets confused by the instruction sequence the compiler
+ * generates for indexing struct fields or arrays. This macro forces the
+ * compiler to generate a code sequence which first calculates the byte offset,
+ * checks it against the struct or array size and add that byte offset to
+ * generate the pointer to the member to help the verifier.
+ *
+ * Ideally, we want to abort if the calculated offset is out-of-bounds. However,
+ * BPF currently doesn't support abort, so evaluate to NULL instead. The caller
+ * must check for NULL and take appropriate action to appease the verifier. To
+ * avoid confusing the verifier, it's best to check for NULL and dereference
+ * immediately.
+ *
+ *	vptr = MEMBER_VPTR(my_array, [i][j]);
+ *	if (!vptr)
+ *		return error;
+ *	*vptr = new_value;
+ */
+#define MEMBER_VPTR(base, member) (typeof(base member) *)({			\
+	u64 __base = (u64)base;							\
+	u64 __addr = (u64)&(base member) - __base;				\
+	asm volatile (								\
+		"if %0 <= %[max] goto +2\n"					\
+		"%0 = 0\n"							\
+		"goto +1\n"							\
+		"%0 += %1\n"							\
+		: "+r"(__addr)							\
+		: "r"(__base),							\
+		  [max]"i"(sizeof(base) - sizeof(base member)));		\
+	__addr;									\
+})
+
+#endif	/* __SCHED_EXT_COMMON_BPF_H */
diff --git a/tools/sched_ext/scx_example_dummy.bpf.c b/tools/sched_ext/scx_example_dummy.bpf.c
new file mode 100644
index 000000000000..ac7b490b5a39
--- /dev/null
+++ b/tools/sched_ext/scx_example_dummy.bpf.c
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * A minimal dummy scheduler.
+ *
+ * In terms of scheduling, this behaves the same as not specifying any ops at
+ * all - a global FIFO. The only things it adds are the following niceties:
+ *
+ * - Statistics tracking how many are queued to local and global dsq's.
+ * - Termination notification for userspace.
+ *
+ * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2022 Tejun Heo <tj@kernel.org>
+ * Copyright (c) 2022 David Vernet <dvernet@meta.com>
+ */
+#include "scx_common.bpf.h"
+
+char _license[] SEC("license") = "GPL";
+
+struct user_exit_info uei;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(key_size, sizeof(u32));
+	__uint(value_size, sizeof(u64));
+	__uint(max_entries, 2);			/* [local, global] */
+} stats SEC(".maps");
+
+static void stat_inc(u32 idx)
+{
+	u64 *cnt_p = bpf_map_lookup_elem(&stats, &idx);
+	if (cnt_p)
+		(*cnt_p)++;
+}
+
+void BPF_STRUCT_OPS(dummy_enqueue, struct task_struct *p, u64 enq_flags)
+{
+	if (enq_flags & SCX_ENQ_LOCAL) {
+		stat_inc(0);
+		scx_bpf_dispatch(p, SCX_DSQ_LOCAL, SCX_SLICE_DFL, enq_flags);
+	} else {
+		stat_inc(1);
+		scx_bpf_dispatch(p, SCX_DSQ_GLOBAL, SCX_SLICE_DFL, enq_flags);
+	}
+}
+
+void BPF_STRUCT_OPS(dummy_exit, struct scx_exit_info *ei)
+{
+	uei_record(&uei, ei);
+}
+
+SEC(".struct_ops")
+struct sched_ext_ops dummy_ops = {
+	.enqueue		= (void *)dummy_enqueue,
+	.exit			= (void *)dummy_exit,
+	.name			= "dummy",
+};
diff --git a/tools/sched_ext/scx_example_dummy.c b/tools/sched_ext/scx_example_dummy.c
new file mode 100644
index 000000000000..72881c881830
--- /dev/null
+++ b/tools/sched_ext/scx_example_dummy.c
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2022 Tejun Heo <tj@kernel.org>
+ * Copyright (c) 2022 David Vernet <dvernet@meta.com>
+ */
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <unistd.h>
+#include <signal.h>
+#include <assert.h>
+#include <libgen.h>
+#include <bpf/bpf.h>
+#include "user_exit_info.h"
+#include "scx_example_dummy.skel.h"
+
+const char help_fmt[] =
+"A minimal dummy sched_ext scheduler.\n"
+"\n"
+"See the top-level comment in .bpf.c for more details.\n"
+"\n"
+"Usage: %s\n"
+"\n"
+"  -h            Display this help and exit\n";
+
+static volatile int exit_req;
+
+static void sigint_handler(int dummy)
+{
+	exit_req = 1;
+}
+
+static void read_stats(struct scx_example_dummy *skel, u64 *stats)
+{
+	int nr_cpus = libbpf_num_possible_cpus();
+	u64 cnts[2][nr_cpus];
+	u32 idx;
+
+	memset(stats, 0, sizeof(stats[0]) * 2);
+
+	for (idx = 0; idx < 2; idx++) {
+		int ret, cpu;
+
+		ret = bpf_map_lookup_elem(bpf_map__fd(skel->maps.stats),
+					  &idx, cnts[idx]);
+		if (ret < 0)
+			continue;
+		for (cpu = 0; cpu < nr_cpus; cpu++)
+			stats[idx] += cnts[idx][cpu];
+	}
+}
+
+int main(int argc, char **argv)
+{
+	struct scx_example_dummy *skel;
+	struct bpf_link *link;
+	u32 opt;
+
+	signal(SIGINT, sigint_handler);
+	signal(SIGTERM, sigint_handler);
+
+	libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
+
+	skel = scx_example_dummy__open();
+	assert(skel);
+
+	while ((opt = getopt(argc, argv, "h")) != -1) {
+		switch (opt) {
+		default:
+			fprintf(stderr, help_fmt, basename(argv[0]));
+			return opt != 'h';
+		}
+	}
+
+	assert(!scx_example_dummy__load(skel));
+
+	link = bpf_map__attach_struct_ops(skel->maps.dummy_ops);
+	assert(link);
+
+	while (!exit_req && !uei_exited(&skel->bss->uei)) {
+		u64 stats[2];
+
+		read_stats(skel, stats);
+		printf("local=%lu global=%lu\n", stats[0], stats[1]);
+		fflush(stdout);
+		sleep(1);
+	}
+
+	bpf_link__destroy(link);
+	uei_print(&skel->bss->uei);
+	scx_example_dummy__destroy(skel);
+	return 0;
+}
diff --git a/tools/sched_ext/scx_example_qmap.bpf.c b/tools/sched_ext/scx_example_qmap.bpf.c
new file mode 100644
index 000000000000..06a07c834b42
--- /dev/null
+++ b/tools/sched_ext/scx_example_qmap.bpf.c
@@ -0,0 +1,238 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * A simple five-level FIFO queue scheduler.
+ *
+ * There are five FIFOs implemented using BPF_MAP_TYPE_QUEUE. A task gets
+ * assigned to one depending on its compound weight. Each CPU round robins
+ * through the FIFOs and dispatches more from FIFOs with higher indices - 1 from
+ * queue0, 2 from queue1, 4 from queue2 and so on.
+ *
+ * This scheduler demonstrates:
+ *
+ * - BPF-side queueing using PIDs.
+ * - Sleepable per-task storage allocation using ops.prep_enable().
+ *
+ * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2022 Tejun Heo <tj@kernel.org>
+ * Copyright (c) 2022 David Vernet <dvernet@meta.com>
+ */
+#include "scx_common.bpf.h"
+#include <linux/sched/prio.h>
+
+char _license[] SEC("license") = "GPL";
+
+const volatile u64 slice_ns = SCX_SLICE_DFL;
+
+u32 test_error_cnt;
+
+struct user_exit_info uei;
+
+struct qmap {
+	__uint(type, BPF_MAP_TYPE_QUEUE);
+	__uint(max_entries, 4096);
+	__type(value, u32);
+} queue0 SEC(".maps"),
+  queue1 SEC(".maps"),
+  queue2 SEC(".maps"),
+  queue3 SEC(".maps"),
+  queue4 SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
+	__uint(max_entries, 5);
+	__type(key, int);
+	__array(values, struct qmap);
+} queue_arr SEC(".maps") = {
+	.values = {
+		[0] = &queue0,
+		[1] = &queue1,
+		[2] = &queue2,
+		[3] = &queue3,
+		[4] = &queue4,
+	},
+};
+
+/* Per-task scheduling context */
+struct task_ctx {
+	bool	force_local;	/* Dispatch directly to local_dsq */
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, struct task_ctx);
+} task_ctx_stor SEC(".maps");
+
+/* Per-cpu dispatch index and remaining count */
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(max_entries, 2);
+	__type(key, u32);
+	__type(value, u64);
+} dispatch_idx_cnt SEC(".maps");
+
+/* Statistics */
+unsigned long nr_enqueued, nr_dispatched, nr_dequeued;
+
+s32 BPF_STRUCT_OPS(qmap_select_cpu, struct task_struct *p,
+		   s32 prev_cpu, u64 wake_flags)
+{
+	struct task_ctx *tctx;
+	s32 cpu;
+
+	tctx = bpf_task_storage_get(&task_ctx_stor, p, 0, 0);
+	if (!tctx) {
+		scx_bpf_error("task_ctx lookup failed");
+		return -ESRCH;
+	}
+
+	if (p->nr_cpus_allowed == 1 ||
+	    scx_bpf_test_and_clear_cpu_idle(prev_cpu)) {
+		tctx->force_local = true;
+		return prev_cpu;
+	}
+
+	cpu = scx_bpf_pick_idle_cpu(p->cpus_ptr);
+	if (cpu >= 0)
+		return cpu;
+
+	return prev_cpu;
+}
+
+static int weight_to_idx(u32 weight)
+{
+	/* Coarsely map the compound weight to a FIFO. */
+	if (weight <= 25)
+		return 0;
+	else if (weight <= 50)
+		return 1;
+	else if (weight < 200)
+		return 2;
+	else if (weight < 400)
+		return 3;
+	else
+		return 4;
+}
+
+void BPF_STRUCT_OPS(qmap_enqueue, struct task_struct *p, u64 enq_flags)
+{
+	struct task_ctx *tctx;
+	u32 pid = p->pid;
+	int idx = weight_to_idx(p->scx.weight);
+	void *ring;
+
+	if (test_error_cnt && !--test_error_cnt)
+		scx_bpf_error("test triggering error");
+
+	tctx = bpf_task_storage_get(&task_ctx_stor, p, 0, 0);
+	if (!tctx) {
+		scx_bpf_error("task_ctx lookup failed");
+		return;
+	}
+
+	/* Is select_cpu() is telling us to enqueue locally? */
+	if (tctx->force_local) {
+		tctx->force_local = false;
+		scx_bpf_dispatch(p, SCX_DSQ_LOCAL, slice_ns, enq_flags);
+		return;
+	}
+
+	ring = bpf_map_lookup_elem(&queue_arr, &idx);
+	if (!ring) {
+		scx_bpf_error("failed to find ring %d", idx);
+		return;
+	}
+
+	/* Queue on the selected FIFO. If the FIFO overflows, punt to global. */
+	if (bpf_map_push_elem(ring, &pid, 0)) {
+		scx_bpf_dispatch(p, SCX_DSQ_GLOBAL, slice_ns, enq_flags);
+		return;
+	}
+
+	__sync_fetch_and_add(&nr_enqueued, 1);
+}
+
+/*
+ * The BPF queue map doesn't support removal and sched_ext can handle spurious
+ * dispatches. qmap_dequeue() is only used to collect statistics.
+ */
+void BPF_STRUCT_OPS(qmap_dequeue, struct task_struct *p, u64 deq_flags)
+{
+	__sync_fetch_and_add(&nr_dequeued, 1);
+}
+
+void BPF_STRUCT_OPS(qmap_dispatch, s32 cpu, struct task_struct *prev)
+{
+	u32 zero = 0, one = 1;
+	u64 *idx = bpf_map_lookup_elem(&dispatch_idx_cnt, &zero);
+	u64 *cnt = bpf_map_lookup_elem(&dispatch_idx_cnt, &one);
+	void *fifo;
+	s32 pid;
+	int i;
+
+	if (!idx || !cnt) {
+		scx_bpf_error("failed to lookup idx[%p], cnt[%p]", idx, cnt);
+		return;
+	}
+
+	for (i = 0; i < 5; i++) {
+		/* Advance the dispatch cursor and pick the fifo. */
+		if (!*cnt) {
+			*idx = (*idx + 1) % 5;
+			*cnt = 1 << *idx;
+		}
+		(*cnt)--;
+
+		fifo = bpf_map_lookup_elem(&queue_arr, idx);
+		if (!fifo) {
+			scx_bpf_error("failed to find ring %llu", *idx);
+			return;
+		}
+
+		/* Dispatch or advance. */
+		if (!bpf_map_pop_elem(fifo, &pid)) {
+			struct task_struct *p;
+
+			p = bpf_task_from_pid(pid);
+			if (p) {
+				__sync_fetch_and_add(&nr_dispatched, 1);
+				scx_bpf_dispatch(p, SCX_DSQ_GLOBAL, slice_ns, 0);
+				bpf_task_release(p);
+				return;
+			}
+		}
+
+		*cnt = 0;
+	}
+}
+
+s32 BPF_STRUCT_OPS(qmap_prep_enable, struct task_struct *p,
+		   struct scx_enable_args *args)
+{
+	/*
+	 * @p is new. Let's ensure that its task_ctx is available. We can sleep
+	 * in this function and the following will automatically use GFP_KERNEL.
+	 */
+	if (bpf_task_storage_get(&task_ctx_stor, p, 0,
+				 BPF_LOCAL_STORAGE_GET_F_CREATE))
+		return 0;
+	else
+		return -ENOMEM;
+}
+
+void BPF_STRUCT_OPS(qmap_exit, struct scx_exit_info *ei)
+{
+	uei_record(&uei, ei);
+}
+
+SEC(".struct_ops")
+struct sched_ext_ops qmap_ops = {
+	.select_cpu		= (void *)qmap_select_cpu,
+	.enqueue		= (void *)qmap_enqueue,
+	.dequeue		= (void *)qmap_dequeue,
+	.dispatch		= (void *)qmap_dispatch,
+	.prep_enable		= (void *)qmap_prep_enable,
+	.exit			= (void *)qmap_exit,
+	.name			= "qmap",
+};
diff --git a/tools/sched_ext/scx_example_qmap.c b/tools/sched_ext/scx_example_qmap.c
new file mode 100644
index 000000000000..c6c74641a182
--- /dev/null
+++ b/tools/sched_ext/scx_example_qmap.c
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2022 Tejun Heo <tj@kernel.org>
+ * Copyright (c) 2022 David Vernet <dvernet@meta.com>
+ */
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <assert.h>
+#include <libgen.h>
+#include <bpf/bpf.h>
+#include "user_exit_info.h"
+#include "scx_example_qmap.skel.h"
+
+const char help_fmt[] =
+"A simple five-level FIFO queue sched_ext scheduler.\n"
+"\n"
+"See the top-level comment in .bpf.c for more details.\n"
+"\n"
+"Usage: %s [-s SLICE_US] [-e COUNT]\n"
+"\n"
+"  -s SLICE_US   Override slice duration\n"
+"  -e COUNT      Trigger scx_bpf_error() after COUNT enqueues\n"
+"  -h            Display this help and exit\n";
+
+static volatile int exit_req;
+
+static void sigint_handler(int dummy)
+{
+	exit_req = 1;
+}
+
+int main(int argc, char **argv)
+{
+	struct scx_example_qmap *skel;
+	struct bpf_link *link;
+	int opt;
+
+	signal(SIGINT, sigint_handler);
+	signal(SIGTERM, sigint_handler);
+
+	libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
+
+	skel = scx_example_qmap__open();
+	assert(skel);
+
+	while ((opt = getopt(argc, argv, "hs:e:tTd:")) != -1) {
+		switch (opt) {
+		case 's':
+			skel->rodata->slice_ns = strtoull(optarg, NULL, 0) * 1000;
+			break;
+		case 'e':
+			skel->bss->test_error_cnt = strtoull(optarg, NULL, 0);
+			break;
+		default:
+			fprintf(stderr, help_fmt, basename(argv[0]));
+			return opt != 'h';
+		}
+	}
+
+	assert(!scx_example_qmap__load(skel));
+
+	link = bpf_map__attach_struct_ops(skel->maps.qmap_ops);
+	assert(link);
+
+	while (!exit_req && !uei_exited(&skel->bss->uei)) {
+		long nr_enqueued = skel->bss->nr_enqueued;
+		long nr_dispatched = skel->bss->nr_dispatched;
+
+		printf("enq=%lu, dsp=%lu, delta=%ld, deq=%lu\n",
+		       nr_enqueued, nr_dispatched, nr_enqueued - nr_dispatched,
+		       skel->bss->nr_dequeued);
+		fflush(stdout);
+		sleep(1);
+	}
+
+	bpf_link__destroy(link);
+	uei_print(&skel->bss->uei);
+	scx_example_qmap__destroy(skel);
+	return 0;
+}
diff --git a/tools/sched_ext/user_exit_info.h b/tools/sched_ext/user_exit_info.h
new file mode 100644
index 000000000000..e701ef0e0b86
--- /dev/null
+++ b/tools/sched_ext/user_exit_info.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Define struct user_exit_info which is shared between BPF and userspace parts
+ * to communicate exit status and other information.
+ *
+ * Copyright (c) 2022 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2022 Tejun Heo <tj@kernel.org>
+ * Copyright (c) 2022 David Vernet <dvernet@meta.com>
+ */
+#ifndef __USER_EXIT_INFO_H
+#define __USER_EXIT_INFO_H
+
+struct user_exit_info {
+	int		type;
+	char		reason[128];
+	char		msg[1024];
+};
+
+#ifdef __bpf__
+
+#include "vmlinux.h"
+#include <bpf/bpf_core_read.h>
+
+static inline void uei_record(struct user_exit_info *uei,
+			      const struct scx_exit_info *ei)
+{
+	bpf_probe_read_kernel_str(uei->reason, sizeof(uei->reason), ei->reason);
+	bpf_probe_read_kernel_str(uei->msg, sizeof(uei->msg), ei->msg);
+	/* use __sync to force memory barrier */
+	__sync_val_compare_and_swap(&uei->type, uei->type, ei->type);
+}
+
+#else	/* !__bpf__ */
+
+static inline bool uei_exited(struct user_exit_info *uei)
+{
+	/* use __sync to force memory barrier */
+	return __sync_val_compare_and_swap(&uei->type, -1, -1);
+}
+
+static inline void uei_print(const struct user_exit_info *uei)
+{
+	fprintf(stderr, "EXIT: %s", uei->reason);
+	if (uei->msg[0] != '\0')
+		fprintf(stderr, " (%s)", uei->msg);
+	fputs("\n", stderr);
+}
+
+#endif	/* __bpf__ */
+#endif	/* __USER_EXIT_INFO_H */
