--- name: "tracefs_hist_continue" section: "3" platform: "linux" package: "libtracefs-doc" version: "1.8.1-1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/tracefs_hist_start" --- # tracefs\_hist\_continue(3) Pause, continue, or clear an existing histogram Part of [tracefs\_hist\_start(3)](/tracefs_hist_start/3.md). ## NAME tracefs\_hist\_start, tracefs\_hist\_destroy, tracefs\_hist\_pause, tracefs\_hist\_continue, tracefs\_hist\_reset - Pause, continue, or clear an existing histogram ## SYNOPSIS ``` #include int tracefs_hist_start(struct tracefs_instance *instance, struct tracefs_hist *hist); int tracefs_hist_destroy(struct tracefs_instance *instance, struct tracefs_hist *hist); int tracefs_hist_pause(struct tracefs_instance *instance, struct tracefs_hist *hist); int tracefs_hist_continue(struct tracefs_instance *instance, struct tracefs_hist *hist); int tracefs_hist_reset(struct tracefs_instance *instance, struct tracefs_hist *hist); ``` ## DESCRIPTION **tracefs\_hist\_start()** is called to actually start the histogram *hist*. The *instance* is the instance to start the histogram in, NULL if it should start at the top level. **tracefs\_hist\_pause()** is called to pause the histogram *hist*. The *instance* is the instance to pause the histogram in, NULL if it is in the top level. **tracefs\_hist\_continue()** is called to continue a paused histogram *hist*. The *instance* is the instance to continue the histogram, NULL if it is in the top level. **tracefs\_hist\_reset()** is called to clear / reset the histogram *hist*. The *instance* is the instance to clear the histogram, NULL if it is in the top level. **tracefs\_hist\_destroy()** is called to delete the histogram where it will no longer exist. The *instance* is the instance to delete the histogram from, NULL if it is in the top level. ## RETURN VALUE All the return zero on success or -1 on error. ## EXAMPLE ``` #include #include enum commands { START, PAUSE, CONT, RESET, DELETE, SHOW, }; int main (int argc, char **argv, char **env) { struct tracefs_instance *instance; struct tracefs_hist *hist; struct tep_handle *tep; enum commands cmd; char *cmd_str; int ret; if (argc < 2) { fprintf(stderr, "usage: %s command\n", argv[0]); exit(-1); } cmd_str = argv[1]; if (!strcmp(cmd_str, "start")) cmd = START; else if (!strcmp(cmd_str, "pause")) cmd = PAUSE; else if (!strcmp(cmd_str, "cont")) cmd = CONT; else if (!strcmp(cmd_str, "reset")) cmd = RESET; else if (!strcmp(cmd_str, "delete")) cmd = DELETE; else if (!strcmp(cmd_str, "show")) cmd = SHOW; else { fprintf(stderr, "Unknown command %s\n", cmd_str); exit(-1); } tep = tracefs_local_events(NULL); if (!tep) { perror("Reading tracefs"); exit(-1); } instance = tracefs_instance_create("hist_test"); if (!instance) { fprintf(stderr, "Failed instance create\n"); exit(-1); } hist = tracefs_hist_alloc_2d(tep, "kmem", "kmalloc", "call_site",TRACEFS_HIST_KEY_SYM, "bytes_req", 0); if (!hist) { fprintf(stderr, "Failed hist create\n"); exit(-1); } ret = tracefs_hist_add_value(hist, "bytes_alloc"); ret |= tracefs_hist_add_sort_key(hist, "bytes_req"); ret |= tracefs_hist_add_sort_key(hist, "bytes_alloc"); ret |= tracefs_hist_sort_key_direction(hist, "bytes_alloc", TRACEFS_HIST_SORT_DESCENDING); if (ret) { fprintf(stderr, "Failed modifying histogram\n"); exit(-1); } tracefs_error_clear(instance); switch (cmd) { case START: ret = tracefs_hist_start(instance, hist); if (ret) { char *err = tracefs_error_last(instance); if (err) fprintf(stderr, "\n%s\n", err); } break; case PAUSE: ret = tracefs_hist_pause(instance, hist); break; case CONT: ret = tracefs_hist_continue(instance, hist); break; case RESET: ret = tracefs_hist_reset(instance, hist); break; case DELETE: ret = tracefs_hist_destroy(instance, hist); break; case SHOW: { char *content; content = tracefs_event_file_read(instance, "kmem", "kmalloc", "hist", NULL); ret = content ? 0 : -1; if (content) { printf("%s\n", content); free(content); } break; } } if (ret) fprintf(stderr, "Failed: command\n"); exit(ret); } ``` ## FILES ``` tracefs.h Header file to include in order to have access to the library APIs. -ltracefs Linker switch to add when building a program that uses the library. ``` ## SEE ALSO [**libtracefs**(3)](/libtracefs/3.md), [**libtraceevent**(3)](/libtraceevent/3.md), [**trace-cmd**(1)](/trace-cmd/1.md), [**tracefs\_hist\_alloc**(3)](/tracefs_hist_alloc/3.md), [**tracefs\_hist\_alloc\_2d**(3)](/tracefs_hist_alloc_2d/3.md), [**tracefs\_hist\_alloc\_nd**(3)](/tracefs_hist_alloc_nd/3.md), [**tracefs\_hist\_free**(3)](/tracefs_hist_free/3.md), [**tracefs\_hist\_add\_key**(3)](/tracefs_hist_add_key/3.md), [**tracefs\_hist\_add\_value**(3)](/tracefs_hist_add_value/3.md), [**tracefs\_hist\_add\_name**(3)](/tracefs_hist_add_name/3.md), [**tracefs\_hist\_start**(3)](/tracefs_hist_start/3.md), **tracefs\_hist\_destory**(3), [**tracefs\_hist\_add\_sort\_key**(3)](/tracefs_hist_add_sort_key/3.md), [**tracefs\_hist\_sort\_key\_direction**(3)](/tracefs_hist_sort_key_direction/3.md) ## AUTHOR ``` Steven Rostedt Tzvetomir Stoyanov sameeruddin shaik ``` ## REPORTING BUGS Report bugs to \<**linux-trace-devel@vger.kernel.org**\[4\]\> ## LICENSE libtracefs is Free Software licensed under the GNU LGPL 2.1 ## RESOURCES **https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/** ## COPYING Copyright (C) 2020 VMware, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL). ## NOTES - 1\. rostedt@goodmis.org mailto:rostedt@goodmis.org - 2\. tz.stoyanov@gmail.com mailto:tz.stoyanov@gmail.com - 3\. sameeruddin.shaik8@gmail.com mailto:sameeruddin.shaik8@gmail.com - 4\. linux-trace-devel@vger.kernel.org mailto:linux-trace-devel@vger.kernel.org