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McKenney" , RCU , "quic_neeraju@quicinc.com" , Boqun Feng , Joel Fernandes , LKML , Oleksiy Avramchenko , Steven Rostedt , Frederic Weisbecker Subject: Re: [PATCH 1/1] Reduce synchronize_rcu() waiting time Message-ID: References: <20230321102748.127923-1-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 22, 2023 at 01:49:50AM +0000, Zhuo, Qiuxu wrote: > Hi Rezki, > > > From: Uladzislau Rezki > > Sent: Tuesday, March 21, 2023 11:16 PM > > [...] > > > > > > > > > If possible, may I know the steps, commands, and related parameters to > > produce the results above? > > > Thank you! > > > > > Build the kernel with CONFIG_RCU_TRACE configuration. Update your > > "set_event" > > file with appropriate traces: > > > > > > XQ-DQ54:/sys/kernel/tracing # echo rcu:rcu_batch_start rcu:rcu_batch_end > > rcu:rcu_invoke_callback > set_event > > > > XQ-DQ54:/sys/kernel/tracing # cat set_event rcu:rcu_batch_start > > rcu:rcu_invoke_callback rcu:rcu_batch_end XQ-DQ54:/sys/kernel/tracing # > > > > > > Collect traces as much as you want: XQ-DQ54:/sys/kernel/tracing # echo 1 > > > tracing_on; sleep 10; echo 0 > tracing_on Next problem is how to parse it. Of > > Thanks for the detailed steps to collect the related testing results. > > > course you will not be able to parse megabytes of traces. For that purpose i > > use a special C trace parser. > > If you need an example please let me know i can show here. > > > > Yes, your example parser should save me from a huge amount of traces. ;-) > Thanks so much for your sharing. > See below the C program. It is ugly but it does what you need. Please have a look at main function: #include #include #include #include #include /* * Splay-tree implementation to store data: key,value * See https://en.wikipedia.org/wiki/Splay_tree */ #define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER) #define container_of(ptr, type, member) \ ({ \ void *__mptr = (void *)(ptr); \ ((type *)(__mptr - offsetof(type, member))); \ }) #define SP_INIT_NODE(node) \ ((node)->left = (node)->right = (node)->parent = NULL) struct splay_node { struct splay_node *left; struct splay_node *right; struct splay_node *parent; unsigned long val; }; struct splay_root { struct splay_node *sp_root; }; static inline void set_parent(struct splay_node *n, struct splay_node *p) { if (n) n->parent = p; } static inline void change_child(struct splay_node *p, struct splay_node *old, struct splay_node *new) { if (p) { if (p->left == old) p->left = new; else p->right = new; } } /* * left rotation of node (r), (rc) is (r)'s right child */ static inline struct splay_node * left_pivot(struct splay_node *r) { struct splay_node *rc; /* * set (rc) to be the new root */ rc = r->right; /* * point parent to new left/right child */ rc->parent = r->parent; /* * change child of the p->parent. */ change_child(r->parent, r, rc); /* * set (r)'s right child to be (rc)'s left child */ r->right = rc->left; /* * change parent of rc's left child */ set_parent(rc->left, r); /* * set new parent of rotated node */ r->parent = rc; /* * set (rc)'s left child to be (r) */ rc->left = r; /* * return the new root */ return rc; } /* * right rotation of node (r), (lc) is (r)'s left child */ static inline struct splay_node * right_pivot(struct splay_node *r) { struct splay_node *lc; /* * set (lc) to be the new root */ lc = r->left; /* * point parent to new left/right child */ lc->parent = r->parent; /* * change child of the p->parent. */ change_child(r->parent, r, lc); /* * set (r)'s left child to be (lc)'s right child */ r->left = lc->right; /* * change parent of lc's right child */ set_parent(lc->right, r); /* * set new parent of rotated node */ r->parent = lc; /* * set (lc)'s right child to be (r) */ lc->right = r; /* * return the new root */ return lc; } static struct splay_node * top_down_splay(unsigned long vstart, struct splay_node *root, struct splay_root *sp_root) { /* * During the splitting process two temporary trees are formed. * "l" contains all keys less than the search key/vstart and "r" * contains all keys greater than the search key/vstart. */ struct splay_node head, *ltree_max, *rtree_max; struct splay_node *ltree_prev, *rtree_prev; if (root == NULL) return NULL; SP_INIT_NODE(&head); ltree_max = rtree_max = &head; ltree_prev = rtree_prev = NULL; while (1) { if (vstart < root->val && root->left) { if (vstart < root->left->val) { root = right_pivot(root); if (root->left == NULL) break; } /* * Build right subtree. */ rtree_max->left = root; rtree_max->left->parent = rtree_prev; rtree_max = rtree_max->left; rtree_prev = root; root = root->left; } else if (vstart > root->val && root->right) { if (vstart > root->right->val) { root = left_pivot(root); if (root->right == NULL) break; } /* * Build left subtree. */ ltree_max->right = root; ltree_max->right->parent = ltree_prev; ltree_max = ltree_max->right; ltree_prev = root; root = root->right; } else { break; } } /* * Assemble the tree. */ ltree_max->right = root->left; rtree_max->left = root->right; root->left = head.right; root->right = head.left; set_parent(ltree_max->right, ltree_max); set_parent(rtree_max->left, rtree_max); set_parent(root->left, root); set_parent(root->right, root); root->parent = NULL; /* * Set new root. Please note it might be the same. */ sp_root->sp_root = root; return sp_root->sp_root; } struct splay_node * splay_search(unsigned long key, struct splay_root *root) { struct splay_node *n; n = top_down_splay(key, root->sp_root, root); if (n && n->val == key) return n; return NULL; } static bool splay_insert(struct splay_node *n, struct splay_root *sp_root) { struct splay_node *r; SP_INIT_NODE(n); r = top_down_splay(n->val, sp_root->sp_root, sp_root); if (r == NULL) { /* First element in the tree */ sp_root->sp_root = n; return false; } if (n->val < r->val) { n->left = r->left; n->right = r; set_parent(r->left, n); r->parent = n; r->left = NULL; } else if (n->val > r->val) { n->right = r->right; n->left = r; set_parent(r->right, n); r->parent = n; r->right = NULL; } else { /* * Same, indicate as not success insertion. */ return false; } sp_root->sp_root = n; return true; } static bool splay_delete_init(struct splay_node *n, struct splay_root *sp_root) { struct splay_node *subtree[2]; unsigned long val = n->val; /* 1. Splay the node to the root. */ n = top_down_splay(n->val, sp_root->sp_root, sp_root); if (n == NULL || n->val != val) return false; /* 2. Save left/right sub-trees. */ subtree[0] = n->left; subtree[1] = n->right; /* 3. Now remove the node. */ SP_INIT_NODE(n); if (subtree[0]) { /* 4. Splay the largest node in left sub-tree to the root. */ top_down_splay(val, subtree[0], sp_root); /* 5. Attach the right sub-tree as the right child of the left sub-tree. */ sp_root->sp_root->right = subtree[1]; /* 6. Update the parent of right sub-tree */ set_parent(subtree[1], sp_root->sp_root); } else { /* 7. Left sub-tree is NULL, just point to right one. */ sp_root->sp_root = subtree[1]; } /* 8. Set parent of root node to NULL. */ if (sp_root->sp_root) sp_root->sp_root->parent = NULL; return true; } static FILE * open_perf_script_file(const char *path) { FILE *f = NULL; if (path == NULL) goto out; f = fopen(path, "r"); if (!f) goto out; out: return f; } static int get_one_line(FILE *file, char *buf, size_t len) { int i = 0; memset(buf, '\0', len); for (i = 0; i < len - 1; i++) { int c = fgetc(file); if (c == EOF) return EOF; if (c == '\n') break; if (c != '\r') buf[i] = c; } return i; } static int read_string_till_string(char *buf, char *out, size_t out_len, char *in, size_t in_len) { int i, j; memset(out, '\0', out_len); for (i = 0; i < out_len; i++) { if (buf[i] != in[0]) { out[i] = buf[i]; continue; } for (j = 0; j < in_len; j++) { if (buf[i + j] != in[j]) break; } /* Found. */ if (j == in_len) return 1; } return 0; } /* * find pattern is "something [003] 8640.034785: something" */ static inline void get_cpu_sec_usec_in_string(const char *s, int *cpu, int *sec, int *usec) { char usec_buf[32] = {'\0'}; char sec_buf[32] = {'\0'}; char cpu_buf[32] = {'\0'}; bool found_sec = false; bool found_usec = false; bool found_cpu = false; int i, j, dot; *cpu = *sec = *usec = -1; for (i = 0, j = 0; s[i] != '\0'; i++) { if (s[i] == '.') { dot = i++; /* take microseconds */ for (j = 0; j < sizeof(usec_buf); j++) { if (isdigit(s[i])) { usec_buf[j] = s[i]; } else { if (s[i] == ':' && j > 0) found_usec = true; else found_usec = false; /* Terminate here. */ break; } i++; } if (found_usec) { /* roll back */ while (s[i] != ' ' && i > 0) i--; /* take seconds */ for (j = 0; j < sizeof(sec_buf); j++) { if (isdigit(s[++i])) { sec_buf[j] = s[i]; } else { if (s[i] == '.' && j > 0) found_sec = true; else found_sec = false; /* Terminate here. */ break; } } } if (found_sec && found_usec) { /* roll back */ while (s[i] != '[' && i > 0) i--; /* take seconds */ for (j = 0; j < sizeof(cpu_buf); j++) { if (isdigit(s[++i])) { cpu_buf[j] = s[i]; } else { if (s[i] == ']' && j > 0) found_cpu = true; else found_cpu = false; /* Terminate here. */ break; } } if (found_cpu && found_sec && found_usec) { *sec = atoi(sec_buf); *usec = atoi(usec_buf); *cpu = atoi(cpu_buf); return; } } /* * Check next dot pattern. */ found_sec = false; found_usec = false; found_cpu = false; i = dot; } } } /* * find pattern is "something comm=foo android thr1 pid=123 something" */ static inline int get_comm_pid_in_string(const char *buf, char *comm, ssize_t len, int *pid) { char *sc, *sp; int rv, i; memset(comm, '\0', len); sc = strstr(buf, "comm="); if (sc) sp = strstr(sc, " pid="); if (!sc || !sp) return -1; for (i = 0, sc += 5; sc != sp; i++) { if (i < len) { if (*sc == ' ') comm[i] = '-'; else comm[i] = *sc; sc++; } } /* Read pid. */ rv = sscanf(sp, " pid=%d", pid); if (rv != 1) return -1; return 1; } static void perf_script_softirq_delay(FILE *file, int delay_usec) { char buf[4096] = { '\0' }; char buf_1[4096] = { '\0' }; long offset; char *s; int rv; while (1) { rv = get_one_line(file, buf, sizeof(buf)); offset = ftell(file); if (rv != EOF) { s = strstr(buf, "irq:softirq_raise:"); if (s) { char extra[512] = {'\0'}; int sec_0, usec_0; int sec_1, usec_1; int handle_vector; int rise_vector; int cpu_0; int cpu_1; /* * swapper 0 [000] 6010.619854: irq:softirq_raise: vec=7 [action=SCHED] * android.bg 3052 [001] 6000.076212: irq:softirq_entry: vec=9 [action=RCU] */ (void) sscanf(s, "%s vec=%d", extra, &rise_vector); get_cpu_sec_usec_in_string(buf, &cpu_0, &sec_0, &usec_0); while (1) { rv = get_one_line(file, buf_1, sizeof(buf_1)); if (rv == EOF) break; s = strstr(buf_1, "irq:softirq_entry:"); if (s) { (void) sscanf(s, "%s vec=%d", extra, &handle_vector); get_cpu_sec_usec_in_string(buf_1, &cpu_1, &sec_1, &usec_1); if (cpu_0 == cpu_1 && rise_vector == handle_vector) { int delta_time_usec = (sec_1 - sec_0) * 1000000 + (usec_1 - usec_0); if (delta_time_usec > delay_usec) fprintf(stdout, "{\n%s\n%s\n} diff %d usec\n", buf, buf_1, delta_time_usec); break; } } } } rv = fseek(file, offset, SEEK_SET); if (rv) fprintf(stdout, "fseek error !!!\n"); } else { break; } } } static void perf_script_softirq_duration(FILE *file, int duration_usec) { char buf[4096] = { '\0' }; char buf_1[4096] = { '\0' }; long offset; char *s; int rv; while (1) { rv = get_one_line(file, buf, sizeof(buf)); offset = ftell(file); if (rv != EOF) { s = strstr(buf, "irq:softirq_entry:"); if (s) { char extra[512] = {'\0'}; int sec_0, usec_0; int sec_1, usec_1; int handle_vector; int rise_vector; int cpu_0; int cpu_1; /* * swapper 0 [000] 6010.619854: irq:softirq_entry: vec=7 [action=SCHED] * android.bg 3052 [001] 6000.076212: irq:softirq_exit: vec=9 [action=RCU] */ (void) sscanf(s, "%s vec=%d", extra, &rise_vector); get_cpu_sec_usec_in_string(buf, &cpu_0, &sec_0, &usec_0); while (1) { rv = get_one_line(file, buf_1, sizeof(buf_1)); if (rv == EOF) break; s = strstr(buf_1, "irq:softirq_exit:"); if (s) { (void) sscanf(s, "%s vec=%d", extra, &handle_vector); get_cpu_sec_usec_in_string(buf_1, &cpu_1, &sec_1, &usec_1); if (cpu_0 == cpu_1 && rise_vector == handle_vector) { int delta_time_usec = (sec_1 - sec_0) * 1000000 + (usec_1 - usec_0); if (delta_time_usec > duration_usec) fprintf(stdout, "{\n%s\n%s\n} diff %d usec\n", buf, buf_1, delta_time_usec); break; } } } } rv = fseek(file, offset, SEEK_SET); if (rv) fprintf(stdout, "fseek error !!!\n"); } else { break; } } } static void perf_script_hardirq_duration(FILE *file, int duration_msec) { char buf[4096] = { '\0' }; char buf_1[4096] = { '\0' }; long offset; char *s; int rv; while (1) { rv = get_one_line(file, buf, sizeof(buf)); offset = ftell(file); if (rv != EOF) { s = strstr(buf, "irq:irq_handler_entry:"); if (s) { char extra[512] = {'\0'}; int sec_0, usec_0; int sec_1, usec_1; int handle_vector; int rise_vector; int cpu_0; int cpu_1; /* * swapper 0 [002] 6205.804133: irq:irq_handler_entry: irq=11 name=arch_timer * swapper 0 [002] 6205.804228: irq:irq_handler_exit: irq=11 ret=handled */ (void) sscanf(s, "%s irq=%d", extra, &rise_vector); get_cpu_sec_usec_in_string(buf, &cpu_0, &sec_0, &usec_0); while (1) { rv = get_one_line(file, buf_1, sizeof(buf_1)); if (rv == EOF) break; s = strstr(buf_1, "irq:irq_handler_exit:"); if (s) { (void) sscanf(s, "%s irq=%d", extra, &handle_vector); get_cpu_sec_usec_in_string(buf_1, &cpu_1, &sec_1, &usec_1); if (cpu_0 == cpu_1 && rise_vector == handle_vector) { int delta_time_usec = (sec_1 - sec_0) * 1000000 + (usec_1 - usec_0); if (delta_time_usec > duration_msec) fprintf(stdout, "{\n%s\n%s\n} diff %d usec\n", buf, buf_1, delta_time_usec); break; } } } } rv = fseek(file, offset, SEEK_SET); if (rv) fprintf(stdout, "fseek error !!!\n"); } else { break; } } } struct irq_stat { int irq; int count; char irq_name[512]; int min_interval; int max_interval; int avg_interval; unsigned int time_stamp_usec; struct splay_node node; }; static struct irq_stat * new_irq_node_init(int irq, char *irq_name) { struct irq_stat *n = calloc(1, sizeof(*n)); if (n) { n->irq = irq; (void) strncpy(n->irq_name, irq_name, sizeof(n->irq_name)); n->node.val = irq; } return n; } static void perf_script_hardirq_stat(FILE *file) { struct splay_root sproot = { NULL }; struct irq_stat *node; char buf[4096] = { '\0' }; char extra[256] = {'\0'}; char irq_name[256] = {'\0'}; unsigned int time_stamp_usec; int cpu, sec, usec; int rv, irq; char *s; while (1) { rv = get_one_line(file, buf, sizeof(buf)); if (rv == EOF) break; s = strstr(buf, "irq:irq_handler_entry:"); if (s == NULL) continue; /* * format is as follow one: * sleep 1418 [003] 8780.957112: irq:irq_handler_entry: irq=11 name=arch_timer */ rv = sscanf(s, "%s irq=%d name=%s", extra, &irq, irq_name); if (rv != 3) continue; get_cpu_sec_usec_in_string(buf, &cpu, &sec, &usec); time_stamp_usec = (sec * 1000000) + usec; if (sproot.sp_root == NULL) { node = new_irq_node_init(irq, irq_name); if (node) splay_insert(&node->node, &sproot); } top_down_splay(irq, sproot.sp_root, &sproot); node = container_of(sproot.sp_root, struct irq_stat, node); /* Found the entry in the tree. */ if (node->irq == irq) { if (node->time_stamp_usec) { unsigned int delta = time_stamp_usec - node->time_stamp_usec; if (delta < node->min_interval || !node->min_interval) node->min_interval = delta; if (delta > node->max_interval) node->max_interval = delta; node->avg_interval += delta; } /* Save the last time for this IRQ entry. */ node->time_stamp_usec = time_stamp_usec; } else { /* Allocate a new record and place it to the tree. */ node = new_irq_node_init(irq, irq_name); if (node) splay_insert(&node->node, &sproot); } /* Update the timestamp for this entry. */ node->time_stamp_usec = time_stamp_usec; node->count++; } /* Dump the tree. */ while (sproot.sp_root) { node = container_of(sproot.sp_root, struct irq_stat, node); fprintf(stdout, "irq: %5d name: %30s count: %7d, min: %10d, max: %10d, avg: %10d\n", node->irq, node->irq_name, node->count, node->min_interval, node->max_interval, node->avg_interval / node->count); splay_delete_init(&node->node, &sproot); free(node); } fprintf(stdout, "\tRun './a.out ./perf.script | sort -nk 6' to sort by column 6.\n"); } struct sched_waking { unsigned int wakeup_nr; char comm[4096]; int pid; int min; int max; int avg; unsigned int time_stamp_usec; struct splay_node node; }; static struct sched_waking * new_sched_waking_node_init(int pid, char *comm) { struct sched_waking *n = calloc(1, sizeof(*n)); if (n) { n->pid = pid; (void) strncpy(n->comm, comm, sizeof(n->comm)); n->node.val = pid; } return n; } /* * How many times a task is awaken + min/max/avg stat. */ static void perf_script_sched_waking_stat(const char *name, FILE *file, const char *script) { struct splay_root sroot = { NULL }; struct sched_waking *n; char buf[4096] = { '\0' }; char comm[256] = {'\0'}; unsigned int time_stamp_usec; unsigned int total_waking = 0; int cpu, sec, usec; int rv, pid; char *s; while (1) { rv = get_one_line(file, buf, sizeof(buf)); if (rv == EOF) break; /* * format is as follow one: * foo[1] 7521 [002] 10.431216: sched_waking: comm=tr pid=2 prio=120 target_cpu=006 */ s = strstr(buf, "sched_waking:"); if (s == NULL) continue; rv = get_comm_pid_in_string(s, comm, sizeof(comm), &pid); if (rv < 0) { printf("ERROR: skip entry...\n"); continue; } get_cpu_sec_usec_in_string(buf, &cpu, &sec, &usec); time_stamp_usec = (sec * 1000000) + usec; if (sroot.sp_root == NULL) { n = new_sched_waking_node_init(pid, comm); if (n) splay_insert(&n->node, &sroot); } top_down_splay(pid, sroot.sp_root, &sroot); n = container_of(sroot.sp_root, struct sched_waking, node); /* Found the entry in the tree. */ if (n->pid == pid) { if (n->time_stamp_usec) { unsigned int delta = time_stamp_usec - n->time_stamp_usec; if (delta < n->min || !n->min) n->min = delta; if (delta > n->max) n->max = delta; n->avg += delta; } /* Save the last time for this wake-up entry. */ n->time_stamp_usec = time_stamp_usec; } else { /* Allocate a new record and place it to the tree. */ n = new_sched_waking_node_init(pid, comm); if (n) splay_insert(&n->node, &sroot); } /* Update the timestamp for this entry. */ n->time_stamp_usec = time_stamp_usec; n->wakeup_nr++; } /* Dump the Splay-tree. */ while (sroot.sp_root) { n = container_of(sroot.sp_root, struct sched_waking, node); fprintf(stdout, "name: %30s pid: %10d woken-up %5d\tinterval: min %5d\tmax %5d\tavg %5d\n", n->comm, n->pid, n->wakeup_nr, n->min, n->max, n->avg / n->wakeup_nr); total_waking += n->wakeup_nr; splay_delete_init(&n->node, &sroot); free(n); } fprintf(stdout, "=== Total: %u ===\n", total_waking); fprintf(stdout, "\tRun './%s %s | sort -nk 6' to sort by column 6.\n", name, script); } /* * Latency of try_to_wake_up path + select a CPU + placing a task into run-queue. */ static void perf_script_sched_wakeup_latency(const char *name, FILE *file, const char *script) { struct splay_root sroot = { NULL }; struct splay_node *node; struct sched_waking *n; char buf[4096] = { '\0' }; char comm[256] = {'\0'}; unsigned int time_stamp_usec; unsigned int wakeup_latency_usec; unsigned int total_waking = 0; int cpu, sec, usec; int rv, pid; char *sched_waking_wakeup; bool sched_waking_event; while (1) { rv = get_one_line(file, buf, sizeof(buf)); if (rv == EOF) break; /* * format is as follow one: * foo[1] 7521 [002] 10.431216: sched_waking: comm=tr pid=2 prio=120 target_cpu=006 */ sched_waking_wakeup = strstr(buf, "sched_waking:"); sched_waking_event = !!sched_waking_wakeup; if (!sched_waking_event) { /* * format is as follow one: * foo[1] 7521 [002] 10.431216: sched_wakeup: comm=tr pid=2 prio=120 target_cpu=006 */ sched_waking_wakeup = strstr(buf, "sched_wakeup:"); if (sched_waking_wakeup == NULL) continue; } rv = get_comm_pid_in_string(sched_waking_wakeup, comm, sizeof(comm), &pid); if (rv < 0) { printf("ERROR: skip entry...\n"); continue; } get_cpu_sec_usec_in_string(buf, &cpu, &sec, &usec); time_stamp_usec = (sec * 1000000) + usec; /* * Let's check if it exists, if so update it * otherwise create a new node and insert. */ if (sched_waking_event) { node = top_down_splay(pid, sroot.sp_root, &sroot); if (node == NULL) { n = new_sched_waking_node_init(pid, comm); splay_insert(&n->node, &sroot); } else { n = container_of(node, struct sched_waking, node); if (n->pid != pid) { n = new_sched_waking_node_init(pid, comm); splay_insert(&n->node, &sroot); } } n->time_stamp_usec = time_stamp_usec; continue; } node = top_down_splay(pid, sroot.sp_root, &sroot); if (node == NULL) { fprintf(stdout, "error: no sched_waking event for %d pid yet.\n", pid); continue; } n = container_of(node, struct sched_waking, node); if (n->pid != pid) { fprintf(stdout, "error: sched_wakeup event does not match with any sched_waking event.\n"); continue; } wakeup_latency_usec = time_stamp_usec - n->time_stamp_usec; if (wakeup_latency_usec < n->min || !n->min) n->min = wakeup_latency_usec; if (wakeup_latency_usec > n->max) n->max = wakeup_latency_usec; if (n->avg + wakeup_latency_usec < n->avg) fprintf(stdout, "error: counter is overflowed...\n"); fprintf(stdout, "%s: %d wake-up latency: %u waken on %d CPU\n", comm, pid, wakeup_latency_usec, cpu); n->avg += wakeup_latency_usec; n->wakeup_nr++; } /* Dump the Splay-tree. */ while (sroot.sp_root) { n = container_of(sroot.sp_root, struct sched_waking, node); /* fprintf(stdout, "name: %30s pid: %10d woken-up %5d\twakeup-latency: min %5d\tmax %5d\tavg %5d\n", */ /* n->comm, n->pid, n->wakeup_nr, */ /* n->min, n->max, n->avg / n->wakeup_nr); */ total_waking += n->wakeup_nr; splay_delete_init(&n->node, &sroot); free(n); } /* fprintf(stdout, "=== Total: %u ===\n", total_waking); */ /* fprintf(stdout, "\tRun '%s %s | sort -nk 6' to sort by column 6.\n", name, script); */ } /* * Requires: * rcu:rcu_batch_start * rcu:rcu_invoke_callback * rcu:rcu_batch_end */ static void perf_script_synchronize_rcu_latency(const char *name, FILE *file, const char *script) { char buf[4096] = { '\0' }; char buf_1[4096] = { '\0' }; long offset; char *s; int rv; while (1) { rv = get_one_line(file, buf, sizeof(buf)); offset = ftell(file); if (rv != EOF) { s = strstr(buf, "rcu_batch_start:"); if (s) { int delta_time_usec; int sec_0, usec_0; int sec_1, usec_1; int pid_0, pid_1; int extra; /* * rcuop/5-58 [007] d..1. 6111.808748: rcu_batch_start: rcu_preempt CBs=23 bl=10 */ (void) sscanf(buf, "%*[^0-9]%d-%d", &pid_0, &pid_0); get_cpu_sec_usec_in_string(buf, &extra, &sec_0, &usec_0); while (1) { rv = get_one_line(file, buf_1, sizeof(buf_1)); if (rv == EOF) break; /* Do not care what a string format is on this step. */ (void) sscanf(buf, "%*[^0-9]%d-%d", &pid_1, &pid_1); /* * rcuop/4-51 [007] d..1. 6111.816758: rcu_batch_end: rcu_preempt CBs-invoked=1 idle=.... */ s = strstr(buf_1, "rcu_batch_end:"); if (s && pid_0 == pid_1) break; /* * rcuop/1-29 [005] ..... 6111.808745: rcu_invoke_callback: rcu_preempt rhp=0000000093881c60 func=file_free_rcu.cfi_jt */ s = strstr(buf_1, "rcu_invoke_callback:"); if (!s || pid_0 != pid_1) continue; s = strstr(buf_1, "wakeme_after_rcu"); if (s) { get_cpu_sec_usec_in_string(buf_1, &extra, &sec_1, &usec_1); delta_time_usec = (sec_1 - sec_0) * 1000000 + (usec_1 - usec_0); fprintf(stdout, "{\n%s\n%s\n} latency %d usec\n", buf, buf_1, delta_time_usec); break; } } } rv = fseek(file, offset, SEEK_SET); if (rv) fprintf(stdout, "fseek error !!!\n"); } else { break; } } } int main(int argc, char **argv) { FILE *file; file = open_perf_script_file(argv[1]); if (file == NULL) { fprintf(stdout, "%s:%d failed: specify a perf script file\n", __func__, __LINE__); exit(-1); } /* perf_script_softirq_delay(file, 1000); */ /* perf_script_softirq_duration(file, 500); */ /* perf_script_hardirq_duration(file, 500); */ /* perf_script_hardirq_stat(file); */ /* perf_script_sched_waking_stat(argv[0], file, argv[1]); */ /* perf_script_sched_wakeup_latency(argv[0], file, argv[1]); */ perf_script_synchronize_rcu_latency(argv[0], file, argv[1]); return 0; } Running it as "./a.out app_launch_rcu_trace.txt" will produce below results: ... { <...>-29 [001] d..1. 21950.145313: rcu_batch_start: rcu_preempt CBs=3613 bl=28 <...>-29 [001] ..... 21950.152583: rcu_invoke_callback: rcu_preempt rhp=000000008f162ca8 func=wakeme_after_rcu.cfi_jt } latency 7270 usec { rcuop/5-58 [005] d..1. 21951.352767: rcu_batch_start: rcu_preempt CBs=3 bl=10 rcuop/5-58 [005] ..... 21951.352768: rcu_invoke_callback: rcu_preempt rhp=00000000b995fac1 func=wakeme_after_rcu.cfi_jt } latency 1 usec { rcuop/6-65 [007] d..1. 21951.804768: rcu_batch_start: rcu_preempt CBs=5 bl=10 rcuop/6-65 [007] ..... 21951.804769: rcu_invoke_callback: rcu_preempt rhp=00000000b995fac1 func=wakeme_after_rcu.cfi_jt } latency 1 usec { rcuop/7-72 [006] d..1. 21951.884774: rcu_batch_start: rcu_preempt CBs=3517 bl=27 rcuop/7-72 [006] ..... 21951.885979: rcu_invoke_callback: rcu_preempt rhp=000000005119eccc func=wakeme_after_rcu.cfi_jt } latency 1205 usec { rcuop/5-58 [007] d..1. 21951.912853: rcu_batch_start: rcu_preempt CBs=193 bl=10 rcuop/5-58 [007] ..... 21951.912975: rcu_invoke_callback: rcu_preempt rhp=00000000b995fac1 func=wakeme_after_rcu.cfi_jt } latency 122 usec ... now you have a pair. -- Uladzislau Rezki