[PATCH v4 06/18] rtla: Simplify code by caching string lengths
From: Wander Lairson Costa <hidden>
Date: 2026-03-09 19:57:03
Also in:
bpf, lkml
Subsystem:
real-time linux analysis (rtla) tools, the rest · Maintainers:
Steven Rostedt, Tomas Glozar, Linus Torvalds
Simplify trace_event_save_hist() and set_comm_cgroup() by computing string lengths once and storing them in local variables, rather than calling strlen() multiple times on the same unchanged strings. This makes the code clearer by eliminating redundant function calls and improving readability. In trace_event_save_hist(), the write loop previously called strlen() on the hist buffer twice per iteration for both the size calculation and loop condition. Store the length in hist_len before entering the loop. In set_comm_cgroup(), strlen() was called on cgroup_path up to three times in succession. Store the result in cg_path_len to use in both the offset calculation and size parameter for subsequent append operations. This simplification makes the code easier to read and maintain without changing program behavior. Signed-off-by: Wander Lairson Costa <redacted> --- tools/tracing/rtla/src/trace.c | 6 ++++-- tools/tracing/rtla/src/utils.c | 11 +++++++---- 2 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/tools/tracing/rtla/src/trace.c b/tools/tracing/rtla/src/trace.c
index e1af54f9531b8..2f529aaf8deef 100644
--- a/tools/tracing/rtla/src/trace.c
+++ b/tools/tracing/rtla/src/trace.c@@ -346,6 +346,7 @@ static void trace_event_save_hist(struct trace_instance *instance, mode_t mode = 0644; char path[MAX_PATH]; char *hist; + size_t hist_len; if (!tevent) return;
@@ -376,9 +377,10 @@ static void trace_event_save_hist(struct trace_instance *instance, } index = 0; + hist_len = strlen(hist); do { - index += write(out_fd, &hist[index], strlen(hist) - index); - } while (index < strlen(hist)); + index += write(out_fd, &hist[index], hist_len - index); + } while (index < hist_len); free(hist); out_close:
diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c
index 75cdcc63d5a15..b5a6007b108d2 100644
--- a/tools/tracing/rtla/src/utils.c
+++ b/tools/tracing/rtla/src/utils.c@@ -811,6 +811,7 @@ static int open_cgroup_procs(const char *cgroup) char cgroup_procs[MAX_PATH]; int retval; int cg_fd; + size_t cg_path_len; retval = find_mount("cgroup2", cgroup_path, sizeof(cgroup_path)); if (!retval) {
@@ -818,16 +819,18 @@ static int open_cgroup_procs(const char *cgroup) return -1; } + cg_path_len = strlen(cgroup_path); + if (!cgroup) { - retval = get_self_cgroup(&cgroup_path[strlen(cgroup_path)], - sizeof(cgroup_path) - strlen(cgroup_path)); + retval = get_self_cgroup(&cgroup_path[cg_path_len], + sizeof(cgroup_path) - cg_path_len); if (!retval) { err_msg("Did not find self cgroup\n"); return -1; } } else { - snprintf(&cgroup_path[strlen(cgroup_path)], - sizeof(cgroup_path) - strlen(cgroup_path), "%s/", cgroup); + snprintf(&cgroup_path[cg_path_len], + sizeof(cgroup_path) - cg_path_len, "%s/", cgroup); } snprintf(cgroup_procs, MAX_PATH, "%s/cgroup.procs", cgroup_path);
--
2.53.0