544 lines · c
1// SPDX-License-Identifier: GPL-2.02#include "util/cgroup.h"3#include "util/debug.h"4#include "util/evlist.h"5#include "util/machine.h"6#include "util/map.h"7#include "util/symbol.h"8#include "util/target.h"9#include "util/thread.h"10#include "util/thread_map.h"11#include "util/lock-contention.h"12#include <linux/zalloc.h>13#include <linux/string.h>14#include <bpf/bpf.h>15#include <inttypes.h>16 17#include "bpf_skel/lock_contention.skel.h"18#include "bpf_skel/lock_data.h"19 20static struct lock_contention_bpf *skel;21 22int lock_contention_prepare(struct lock_contention *con)23{24 int i, fd;25 int ncpus = 1, ntasks = 1, ntypes = 1, naddrs = 1, ncgrps = 1;26 struct evlist *evlist = con->evlist;27 struct target *target = con->target;28 29 skel = lock_contention_bpf__open();30 if (!skel) {31 pr_err("Failed to open lock-contention BPF skeleton\n");32 return -1;33 }34 35 bpf_map__set_value_size(skel->maps.stacks, con->max_stack * sizeof(u64));36 bpf_map__set_max_entries(skel->maps.lock_stat, con->map_nr_entries);37 bpf_map__set_max_entries(skel->maps.tstamp, con->map_nr_entries);38 39 if (con->aggr_mode == LOCK_AGGR_TASK)40 bpf_map__set_max_entries(skel->maps.task_data, con->map_nr_entries);41 else42 bpf_map__set_max_entries(skel->maps.task_data, 1);43 44 if (con->save_callstack)45 bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries);46 else47 bpf_map__set_max_entries(skel->maps.stacks, 1);48 49 if (target__has_cpu(target)) {50 skel->rodata->has_cpu = 1;51 ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus);52 }53 if (target__has_task(target)) {54 skel->rodata->has_task = 1;55 ntasks = perf_thread_map__nr(evlist->core.threads);56 }57 if (con->filters->nr_types) {58 skel->rodata->has_type = 1;59 ntypes = con->filters->nr_types;60 }61 if (con->filters->nr_cgrps) {62 skel->rodata->has_cgroup = 1;63 ncgrps = con->filters->nr_cgrps;64 }65 66 /* resolve lock name filters to addr */67 if (con->filters->nr_syms) {68 struct symbol *sym;69 struct map *kmap;70 unsigned long *addrs;71 72 for (i = 0; i < con->filters->nr_syms; i++) {73 sym = machine__find_kernel_symbol_by_name(con->machine,74 con->filters->syms[i],75 &kmap);76 if (sym == NULL) {77 pr_warning("ignore unknown symbol: %s\n",78 con->filters->syms[i]);79 continue;80 }81 82 addrs = realloc(con->filters->addrs,83 (con->filters->nr_addrs + 1) * sizeof(*addrs));84 if (addrs == NULL) {85 pr_warning("memory allocation failure\n");86 continue;87 }88 89 addrs[con->filters->nr_addrs++] = map__unmap_ip(kmap, sym->start);90 con->filters->addrs = addrs;91 }92 naddrs = con->filters->nr_addrs;93 skel->rodata->has_addr = 1;94 }95 96 bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);97 bpf_map__set_max_entries(skel->maps.task_filter, ntasks);98 bpf_map__set_max_entries(skel->maps.type_filter, ntypes);99 bpf_map__set_max_entries(skel->maps.addr_filter, naddrs);100 bpf_map__set_max_entries(skel->maps.cgroup_filter, ncgrps);101 102 skel->rodata->stack_skip = con->stack_skip;103 skel->rodata->aggr_mode = con->aggr_mode;104 skel->rodata->needs_callstack = con->save_callstack;105 skel->rodata->lock_owner = con->owner;106 107 if (con->aggr_mode == LOCK_AGGR_CGROUP || con->filters->nr_cgrps) {108 if (cgroup_is_v2("perf_event"))109 skel->rodata->use_cgroup_v2 = 1;110 }111 112 if (lock_contention_bpf__load(skel) < 0) {113 pr_err("Failed to load lock-contention BPF skeleton\n");114 return -1;115 }116 117 if (target__has_cpu(target)) {118 u32 cpu;119 u8 val = 1;120 121 fd = bpf_map__fd(skel->maps.cpu_filter);122 123 for (i = 0; i < ncpus; i++) {124 cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu;125 bpf_map_update_elem(fd, &cpu, &val, BPF_ANY);126 }127 }128 129 if (target__has_task(target)) {130 u32 pid;131 u8 val = 1;132 133 fd = bpf_map__fd(skel->maps.task_filter);134 135 for (i = 0; i < ntasks; i++) {136 pid = perf_thread_map__pid(evlist->core.threads, i);137 bpf_map_update_elem(fd, &pid, &val, BPF_ANY);138 }139 }140 141 if (target__none(target) && evlist->workload.pid > 0) {142 u32 pid = evlist->workload.pid;143 u8 val = 1;144 145 fd = bpf_map__fd(skel->maps.task_filter);146 bpf_map_update_elem(fd, &pid, &val, BPF_ANY);147 }148 149 if (con->filters->nr_types) {150 u8 val = 1;151 152 fd = bpf_map__fd(skel->maps.type_filter);153 154 for (i = 0; i < con->filters->nr_types; i++)155 bpf_map_update_elem(fd, &con->filters->types[i], &val, BPF_ANY);156 }157 158 if (con->filters->nr_addrs) {159 u8 val = 1;160 161 fd = bpf_map__fd(skel->maps.addr_filter);162 163 for (i = 0; i < con->filters->nr_addrs; i++)164 bpf_map_update_elem(fd, &con->filters->addrs[i], &val, BPF_ANY);165 }166 167 if (con->filters->nr_cgrps) {168 u8 val = 1;169 170 fd = bpf_map__fd(skel->maps.cgroup_filter);171 172 for (i = 0; i < con->filters->nr_cgrps; i++)173 bpf_map_update_elem(fd, &con->filters->cgrps[i], &val, BPF_ANY);174 }175 176 if (con->aggr_mode == LOCK_AGGR_CGROUP)177 read_all_cgroups(&con->cgroups);178 179 bpf_program__set_autoload(skel->progs.collect_lock_syms, false);180 181 lock_contention_bpf__attach(skel);182 return 0;183}184 185/*186 * Run the BPF program directly using BPF_PROG_TEST_RUN to update the end187 * timestamp in ktime so that it can calculate delta easily.188 */189static void mark_end_timestamp(void)190{191 DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,192 .flags = BPF_F_TEST_RUN_ON_CPU,193 );194 int prog_fd = bpf_program__fd(skel->progs.end_timestamp);195 196 bpf_prog_test_run_opts(prog_fd, &opts);197}198 199static void update_lock_stat(int map_fd, int pid, u64 end_ts,200 enum lock_aggr_mode aggr_mode,201 struct tstamp_data *ts_data)202{203 u64 delta;204 struct contention_key stat_key = {};205 struct contention_data stat_data;206 207 if (ts_data->timestamp >= end_ts)208 return;209 210 delta = end_ts - ts_data->timestamp;211 212 switch (aggr_mode) {213 case LOCK_AGGR_CALLER:214 stat_key.stack_id = ts_data->stack_id;215 break;216 case LOCK_AGGR_TASK:217 stat_key.pid = pid;218 break;219 case LOCK_AGGR_ADDR:220 stat_key.lock_addr_or_cgroup = ts_data->lock;221 break;222 case LOCK_AGGR_CGROUP:223 /* TODO */224 return;225 default:226 return;227 }228 229 if (bpf_map_lookup_elem(map_fd, &stat_key, &stat_data) < 0)230 return;231 232 stat_data.total_time += delta;233 stat_data.count++;234 235 if (delta > stat_data.max_time)236 stat_data.max_time = delta;237 if (delta < stat_data.min_time)238 stat_data.min_time = delta;239 240 bpf_map_update_elem(map_fd, &stat_key, &stat_data, BPF_EXIST);241}242 243/*244 * Account entries in the tstamp map (which didn't see the corresponding245 * lock:contention_end tracepoint) using end_ts.246 */247static void account_end_timestamp(struct lock_contention *con)248{249 int ts_fd, stat_fd;250 int *prev_key, key;251 u64 end_ts = skel->bss->end_ts;252 int total_cpus;253 enum lock_aggr_mode aggr_mode = con->aggr_mode;254 struct tstamp_data ts_data, *cpu_data;255 256 /* Iterate per-task tstamp map (key = TID) */257 ts_fd = bpf_map__fd(skel->maps.tstamp);258 stat_fd = bpf_map__fd(skel->maps.lock_stat);259 260 prev_key = NULL;261 while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) {262 if (bpf_map_lookup_elem(ts_fd, &key, &ts_data) == 0) {263 int pid = key;264 265 if (aggr_mode == LOCK_AGGR_TASK && con->owner)266 pid = ts_data.flags;267 268 update_lock_stat(stat_fd, pid, end_ts, aggr_mode,269 &ts_data);270 }271 272 prev_key = &key;273 }274 275 /* Now it'll check per-cpu tstamp map which doesn't have TID. */276 if (aggr_mode == LOCK_AGGR_TASK || aggr_mode == LOCK_AGGR_CGROUP)277 return;278 279 total_cpus = cpu__max_cpu().cpu;280 ts_fd = bpf_map__fd(skel->maps.tstamp_cpu);281 282 cpu_data = calloc(total_cpus, sizeof(*cpu_data));283 if (cpu_data == NULL)284 return;285 286 prev_key = NULL;287 while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) {288 if (bpf_map_lookup_elem(ts_fd, &key, cpu_data) < 0)289 goto next;290 291 for (int i = 0; i < total_cpus; i++) {292 if (cpu_data[i].lock == 0)293 continue;294 295 update_lock_stat(stat_fd, -1, end_ts, aggr_mode,296 &cpu_data[i]);297 }298 299next:300 prev_key = &key;301 }302 free(cpu_data);303}304 305int lock_contention_start(void)306{307 skel->bss->enabled = 1;308 return 0;309}310 311int lock_contention_stop(void)312{313 skel->bss->enabled = 0;314 mark_end_timestamp();315 return 0;316}317 318static const char *lock_contention_get_name(struct lock_contention *con,319 struct contention_key *key,320 u64 *stack_trace, u32 flags)321{322 int idx = 0;323 u64 addr;324 const char *name = "";325 static char name_buf[KSYM_NAME_LEN];326 struct symbol *sym;327 struct map *kmap;328 struct machine *machine = con->machine;329 330 if (con->aggr_mode == LOCK_AGGR_TASK) {331 struct contention_task_data task;332 int pid = key->pid;333 int task_fd = bpf_map__fd(skel->maps.task_data);334 335 /* do not update idle comm which contains CPU number */336 if (pid) {337 struct thread *t = machine__findnew_thread(machine, /*pid=*/-1, pid);338 339 if (t == NULL)340 return name;341 if (!bpf_map_lookup_elem(task_fd, &pid, &task) &&342 thread__set_comm(t, task.comm, /*timestamp=*/0))343 name = task.comm;344 }345 return name;346 }347 348 if (con->aggr_mode == LOCK_AGGR_ADDR) {349 int lock_fd = bpf_map__fd(skel->maps.lock_syms);350 351 /* per-process locks set upper bits of the flags */352 if (flags & LCD_F_MMAP_LOCK)353 return "mmap_lock";354 if (flags & LCD_F_SIGHAND_LOCK)355 return "siglock";356 357 /* global locks with symbols */358 sym = machine__find_kernel_symbol(machine, key->lock_addr_or_cgroup, &kmap);359 if (sym)360 return sym->name;361 362 /* try semi-global locks collected separately */363 if (!bpf_map_lookup_elem(lock_fd, &key->lock_addr_or_cgroup, &flags)) {364 if (flags == LOCK_CLASS_RQLOCK)365 return "rq_lock";366 }367 368 return "";369 }370 371 if (con->aggr_mode == LOCK_AGGR_CGROUP) {372 u64 cgrp_id = key->lock_addr_or_cgroup;373 struct cgroup *cgrp = __cgroup__find(&con->cgroups, cgrp_id);374 375 if (cgrp)376 return cgrp->name;377 378 snprintf(name_buf, sizeof(name_buf), "cgroup:%" PRIu64 "", cgrp_id);379 return name_buf;380 }381 382 /* LOCK_AGGR_CALLER: skip lock internal functions */383 while (machine__is_lock_function(machine, stack_trace[idx]) &&384 idx < con->max_stack - 1)385 idx++;386 387 addr = stack_trace[idx];388 sym = machine__find_kernel_symbol(machine, addr, &kmap);389 390 if (sym) {391 unsigned long offset;392 393 offset = map__map_ip(kmap, addr) - sym->start;394 395 if (offset == 0)396 return sym->name;397 398 snprintf(name_buf, sizeof(name_buf), "%s+%#lx", sym->name, offset);399 } else {400 snprintf(name_buf, sizeof(name_buf), "%#lx", (unsigned long)addr);401 }402 403 return name_buf;404}405 406int lock_contention_read(struct lock_contention *con)407{408 int fd, stack, err = 0;409 struct contention_key *prev_key, key = {};410 struct contention_data data = {};411 struct lock_stat *st = NULL;412 struct machine *machine = con->machine;413 u64 *stack_trace;414 size_t stack_size = con->max_stack * sizeof(*stack_trace);415 416 fd = bpf_map__fd(skel->maps.lock_stat);417 stack = bpf_map__fd(skel->maps.stacks);418 419 con->fails.task = skel->bss->task_fail;420 con->fails.stack = skel->bss->stack_fail;421 con->fails.time = skel->bss->time_fail;422 con->fails.data = skel->bss->data_fail;423 424 stack_trace = zalloc(stack_size);425 if (stack_trace == NULL)426 return -1;427 428 account_end_timestamp(con);429 430 if (con->aggr_mode == LOCK_AGGR_TASK) {431 struct thread *idle = machine__findnew_thread(machine,432 /*pid=*/0,433 /*tid=*/0);434 thread__set_comm(idle, "swapper", /*timestamp=*/0);435 }436 437 if (con->aggr_mode == LOCK_AGGR_ADDR) {438 DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,439 .flags = BPF_F_TEST_RUN_ON_CPU,440 );441 int prog_fd = bpf_program__fd(skel->progs.collect_lock_syms);442 443 bpf_prog_test_run_opts(prog_fd, &opts);444 }445 446 /* make sure it loads the kernel map */447 maps__load_first(machine->kmaps);448 449 prev_key = NULL;450 while (!bpf_map_get_next_key(fd, prev_key, &key)) {451 s64 ls_key;452 const char *name;453 454 /* to handle errors in the loop body */455 err = -1;456 457 bpf_map_lookup_elem(fd, &key, &data);458 if (con->save_callstack) {459 bpf_map_lookup_elem(stack, &key.stack_id, stack_trace);460 461 if (!match_callstack_filter(machine, stack_trace)) {462 con->nr_filtered += data.count;463 goto next;464 }465 }466 467 switch (con->aggr_mode) {468 case LOCK_AGGR_CALLER:469 ls_key = key.stack_id;470 break;471 case LOCK_AGGR_TASK:472 ls_key = key.pid;473 break;474 case LOCK_AGGR_ADDR:475 case LOCK_AGGR_CGROUP:476 ls_key = key.lock_addr_or_cgroup;477 break;478 default:479 goto next;480 }481 482 st = lock_stat_find(ls_key);483 if (st != NULL) {484 st->wait_time_total += data.total_time;485 if (st->wait_time_max < data.max_time)486 st->wait_time_max = data.max_time;487 if (st->wait_time_min > data.min_time)488 st->wait_time_min = data.min_time;489 490 st->nr_contended += data.count;491 if (st->nr_contended)492 st->avg_wait_time = st->wait_time_total / st->nr_contended;493 goto next;494 }495 496 name = lock_contention_get_name(con, &key, stack_trace, data.flags);497 st = lock_stat_findnew(ls_key, name, data.flags);498 if (st == NULL)499 break;500 501 st->nr_contended = data.count;502 st->wait_time_total = data.total_time;503 st->wait_time_max = data.max_time;504 st->wait_time_min = data.min_time;505 506 if (data.count)507 st->avg_wait_time = data.total_time / data.count;508 509 if (con->aggr_mode == LOCK_AGGR_CALLER && verbose > 0) {510 st->callstack = memdup(stack_trace, stack_size);511 if (st->callstack == NULL)512 break;513 }514 515next:516 prev_key = &key;517 518 /* we're fine now, reset the error */519 err = 0;520 }521 522 free(stack_trace);523 524 return err;525}526 527int lock_contention_finish(struct lock_contention *con)528{529 if (skel) {530 skel->bss->enabled = 0;531 lock_contention_bpf__destroy(skel);532 }533 534 while (!RB_EMPTY_ROOT(&con->cgroups)) {535 struct rb_node *node = rb_first(&con->cgroups);536 struct cgroup *cgrp = rb_entry(node, struct cgroup, node);537 538 rb_erase(node, &con->cgroups);539 cgroup__put(cgrp);540 }541 542 return 0;543}544