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Merge pull request #1677 from dave-tucker/revert-ringbuf
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Revert "Merge pull request #1628 from dave-tucker/new-ebpf"
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@sthaha
sthaha authored Aug 8, 2024
2 parents 39ef719 + 6c32e7f commit 9a322d3
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Showing 122 changed files with 1,671 additions and 2,926 deletions.
7 changes: 4 additions & 3 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -176,6 +176,7 @@ build: clean_build_local _build_local copy_build_local ## Build binary and copy
.PHONY: generate
generate: ## Generate BPF code locally.
+@$(GOENV) go generate ./pkg/bpf
+@$(GOENV) go generate ./pkg/bpftest

_build_local: generate ## Build Kepler binary locally.
@echo TAGS=$(GO_BUILD_TAGS)
Expand Down Expand Up @@ -274,7 +275,7 @@ container_test:

TEST_PKGS := $(shell go list -tags $(GO_BUILD_TAGS) ./... | grep -v pkg/bpf | grep -v e2e)
SUDO?=sudo
SUDO_TEST_PKGS := $(shell go list -tags $(GO_BUILD_TAGS) ./... | grep pkg/bpf)
SUDO_TEST_PKGS := $(shell go list -tags $(GO_BUILD_TAGS) ./... | grep pkg/bpftest)

##@ testing

Expand Down Expand Up @@ -304,9 +305,9 @@ bpf-test: generate ginkgo-set ## Run BPF tests.$(GOBIN)
-tags $(GO_TEST_TAGS) \
-cover \
--covermode=atomic \
./pkg/bpf
./pkg/bpftest
$(SUDO) $(ENVTEST_ASSETS_DIR)/ginkgo \
./pkg/bpf/bpf.test
./pkg/bpftest/bpftest.test

escapes_detect: tidy-vendor
@$(GOENV) go build -tags $(GO_BUILD_TAGS) -gcflags="-m -l" ./... 2>&1 | grep "escapes to heap" || true
Expand Down
207 changes: 8 additions & 199 deletions bpf/kepler.bpf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3,168 +3,6 @@

#include "kepler.bpf.h"

// Ring buffer sizing
// 256kB is sufficient to store around 1000 events/sec for 5 seconds
struct {
__uint(type, BPF_MAP_TYPE_RINGBUF);
__uint(max_entries, 256 * 1024); // 256 KB
} rb SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__type(key, int);
__type(value, u32);
} cpu_cycles_event_reader SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__type(key, int);
__type(value, u32);
} cpu_instructions_event_reader SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__type(key, int);
__type(value, u32);
} cache_miss_event_reader SEC(".maps");

SEC(".rodata.config")
__attribute__((btf_decl_tag("Hardware Events Enabled"))) volatile const int HW = 1;

static __always_inline u64 get_on_cpu_cycles(u32 *cpu_id)
{
long error;
struct bpf_perf_event_value c = {};

error = bpf_perf_event_read_value(
&cpu_cycles_event_reader, *cpu_id, &c, sizeof(c));
if (error)
return 0;

return c.counter;
}

static __always_inline u64 get_on_cpu_instr(u32 *cpu_id)
{
long error;
struct bpf_perf_event_value c = {};

error = bpf_perf_event_read_value(
&cpu_instructions_event_reader, *cpu_id, &c, sizeof(c));
if (error)
return 0;

return c.counter;
}

static __always_inline u64 get_on_cpu_cache_miss(u32 *cpu_id)
{
long error;
struct bpf_perf_event_value c = {};

error = bpf_perf_event_read_value(
&cache_miss_event_reader, *cpu_id, &c, sizeof(c));
if (error)
return 0;

return c.counter;
}

// Wake up userspace if there are at least 1000 events unprocessed
const long wakeup_data_size = sizeof(struct event) * 1000;

// Get the flags for the ring buffer submit
static inline long get_flags()
{
long sz;

if (!wakeup_data_size)
return 0;

sz = bpf_ringbuf_query(&rb, BPF_RB_AVAIL_DATA);
return sz >= wakeup_data_size ? BPF_RB_FORCE_WAKEUP : BPF_RB_NO_WAKEUP;
}

static inline int do_kepler_sched_switch_trace(
u32 prev_pid, u32 prev_tgid, u32 next_pid, u32 next_tgid)
{
struct event *e;
u64 cpu_cycles, cpu_instr, cache_miss = 0;

e = bpf_ringbuf_reserve(&rb, sizeof(*e), 0);
if (!e)
return 0;

e->ts = bpf_ktime_get_ns();
e->event_type = SCHED_SWITCH;
e->cpu_id = bpf_get_smp_processor_id();
e->pid = next_tgid;
e->tid = next_pid;
e->offcpu_pid = prev_tgid;
e->offcpu_tid = prev_pid;
if (HW) {
e->cpu_cycles = get_on_cpu_cycles(&e->cpu_id);
e->cpu_instr = get_on_cpu_instr(&e->cpu_id);
e->cache_miss = get_on_cpu_cache_miss(&e->cpu_id);
}
e->offcpu_cgroup_id = bpf_get_current_cgroup_id();

bpf_ringbuf_submit(e, get_flags());

return 0;
}

static inline int do_kepler_irq_trace(u32 vec)
{
struct event *e;

// We are interested in NET_TX, NET_RX, and BLOCK
if (vec == NET_TX || vec == NET_RX || vec == BLOCK) {
e = bpf_ringbuf_reserve(&rb, sizeof(*e), 0);
if (!e)
return 0;
e->event_type = IRQ;
e->ts = bpf_ktime_get_ns();
e->cpu_id = bpf_get_smp_processor_id();
e->pid = bpf_get_current_pid_tgid() >> 32;
e->tid = (u32)bpf_get_current_pid_tgid();
e->irq_number = vec;

bpf_ringbuf_submit(e, get_flags());
}

return 0;
}

static inline int do_page_cache_hit_increment(u32 curr_tgid)
{
struct event *e;

e = bpf_ringbuf_reserve(&rb, sizeof(*e), 0);
if (!e)
return 0;
e->event_type = PAGE_CACHE_HIT;
e->ts = bpf_ktime_get_ns();
e->pid = curr_tgid;

bpf_ringbuf_submit(e, get_flags());

return 0;
}

static inline int do_process_free(u32 curr_tgid)
{
struct event *e;

e = bpf_ringbuf_reserve(&rb, sizeof(*e), 0);
if (!e)
return 0;
e->event_type = FREE;
e->ts = bpf_ktime_get_ns();
e->pid = curr_tgid;

bpf_ringbuf_submit(e, get_flags());

return 0;
}

SEC("tp_btf/sched_switch")
int kepler_sched_switch_trace(u64 *ctx)
{
Expand All @@ -174,17 +12,21 @@ int kepler_sched_switch_trace(u64 *ctx)
next_task = (struct task_struct *)ctx[2];

return do_kepler_sched_switch_trace(
prev_task->pid, prev_task->tgid, next_task->pid, next_task->tgid);
prev_task->pid, next_task->pid, prev_task->tgid, next_task->tgid);
}

SEC("tp_btf/softirq_entry")
int kepler_irq_trace(u64 *ctx)
{
u32 curr_tgid;
struct process_metrics_t *process_metrics;
unsigned int vec;
vec = (unsigned int)ctx[0];

do_kepler_irq_trace(vec);

curr_tgid = bpf_get_current_pid_tgid() >> 32;
vec = (unsigned int)ctx[0];
process_metrics = bpf_map_lookup_elem(&processes, &curr_tgid);
if (process_metrics != 0 && vec < 10)
process_metrics->vec_nr[vec] += 1;
return 0;
}

Expand All @@ -210,37 +52,4 @@ int kepler_write_page_trace(void *ctx)
return 0;
}

SEC("tp_btf/sched_process_free")
int kepler_sched_process_free(u64 *ctx)
{
struct task_struct *task;
task = (struct task_struct *)ctx[0];
do_process_free(task->tgid);
return 0;
}

// TEST PROGRAMS - These programs are never attached in production

SEC("raw_tp")
int test_kepler_write_page_trace(void *ctx)
{
do_page_cache_hit_increment(42);
return 0;
}

SEC("raw_tp")
int test_kepler_sched_switch_trace(u64 *ctx)
{
// 42 going offcpu, 43 going on cpu
do_kepler_sched_switch_trace(42, 42, 43, 43);
return 0;
}

SEC("raw_tp")
int test_kepler_sched_process_free(u64 *ctx)
{
do_process_free(42);
return 0;
}

char __license[] SEC("license") = "Dual BSD/GPL";
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