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Message-ID: <20240815140509.12468-4-tglozar@redhat.com>
Date: Thu, 15 Aug 2024 16:05:06 +0200
From: tglozar@...hat.com
To: rostedt@...dmis.org
Cc: linux-trace-kernel@...r.kernel.org,
linux-kernel@...r.kernel.org,
jwyatt@...hat.com,
jkacur@...hat.com,
Tomas Glozar <tglozar@...hat.com>
Subject: [PATCH v3 3/6] rtla/utils: Add idle state disabling via libcpupower
From: Tomas Glozar <tglozar@...hat.com>
Add functions to utils.c to disable idle states through functions of
libcpupower. This will serve as the basis for disabling idle states
per cpu when running timerlat.
Signed-off-by: Tomas Glozar <tglozar@...hat.com>
---
tools/tracing/rtla/src/utils.c | 150 +++++++++++++++++++++++++++++++++
tools/tracing/rtla/src/utils.h | 13 +++
2 files changed, 163 insertions(+)
diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c
index 9ac71a66840c..6ae084fdedf9 100644
--- a/tools/tracing/rtla/src/utils.c
+++ b/tools/tracing/rtla/src/utils.c
@@ -4,6 +4,9 @@
*/
#define _GNU_SOURCE
+#ifdef HAVE_LIBCPUPOWER_SUPPORT
+#include <cpuidle.h>
+#endif /* HAVE_LIBCPUPOWER_SUPPORT */
#include <dirent.h>
#include <stdarg.h>
#include <stdlib.h>
@@ -519,6 +522,153 @@ int set_cpu_dma_latency(int32_t latency)
return fd;
}
+#ifdef HAVE_LIBCPUPOWER_SUPPORT
+static unsigned int **saved_cpu_idle_disable_state;
+static size_t saved_cpu_idle_disable_state_alloc_ctr;
+
+/*
+ * save_cpu_idle_state_disable - save disable for all idle states of a cpu
+ *
+ * Saves the current disable of all idle states of a cpu, to be subsequently
+ * restored via restore_cpu_idle_disable_state.
+ *
+ * Return: idle state count on success, negative on error
+ */
+int save_cpu_idle_disable_state(unsigned int cpu)
+{
+ unsigned int nr_states;
+ unsigned int state;
+ int disabled;
+ int nr_cpus;
+
+ nr_states = cpuidle_state_count(cpu);
+
+ if (nr_states == 0)
+ return 0;
+
+ if (saved_cpu_idle_disable_state == NULL) {
+ nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+ saved_cpu_idle_disable_state = calloc(nr_cpus, sizeof(unsigned int *));
+ if (!saved_cpu_idle_disable_state)
+ return -1;
+ }
+
+ saved_cpu_idle_disable_state[cpu] = calloc(nr_states, sizeof(unsigned int));
+ if (!saved_cpu_idle_disable_state[cpu])
+ return -1;
+ saved_cpu_idle_disable_state_alloc_ctr++;
+
+ for (state = 0; state < nr_states; state++) {
+ disabled = cpuidle_is_state_disabled(cpu, state);
+ if (disabled < 0)
+ return disabled;
+ saved_cpu_idle_disable_state[cpu][state] = disabled;
+ }
+
+ return nr_states;
+}
+
+/*
+ * restore_cpu_idle_disable_state - restore disable for all idle states of a cpu
+ *
+ * Restores the current disable state of all idle states of a cpu that was
+ * previously saved by save_cpu_idle_disable_state.
+ *
+ * Return: idle state count on success, negative on error
+ */
+int restore_cpu_idle_disable_state(unsigned int cpu)
+{
+ unsigned int nr_states;
+ unsigned int state;
+ int disabled;
+ int result;
+
+ if (!saved_cpu_idle_disable_state)
+ return -1;
+
+ nr_states = cpuidle_state_count(cpu);
+
+ if (nr_states == 0)
+ return 0;
+
+ for (state = 0; state < nr_states; state++) {
+ if (!saved_cpu_idle_disable_state[cpu])
+ return -1;
+ disabled = saved_cpu_idle_disable_state[cpu][state];
+ result = cpuidle_state_disable(cpu, state, disabled);
+ if (result < 0)
+ return result;
+ }
+
+ free(saved_cpu_idle_disable_state[cpu]);
+ saved_cpu_idle_disable_state[cpu] = NULL;
+ saved_cpu_idle_disable_state_alloc_ctr--;
+ if (saved_cpu_idle_disable_state_alloc_ctr == 0) {
+ free(saved_cpu_idle_disable_state);
+ saved_cpu_idle_disable_state = NULL;
+ }
+
+ return nr_states;
+}
+
+/*
+ * free_cpu_idle_disable_states - free saved idle state disable for all cpus
+ *
+ * Frees the memory used for storing cpu idle state disable for all cpus
+ * and states.
+ *
+ * Normally, the memory is freed automatically in
+ * restore_cpu_idle_disable_state; this is mostly for cleaning up after an
+ * error.
+ */
+void free_cpu_idle_disable_states(void)
+{
+ int cpu;
+ int nr_cpus;
+
+ if (!saved_cpu_idle_disable_state)
+ return;
+
+ nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+
+ for (cpu = 0; cpu < nr_cpus; cpu++) {
+ free(saved_cpu_idle_disable_state[cpu]);
+ saved_cpu_idle_disable_state[cpu] = NULL;
+ }
+
+ free(saved_cpu_idle_disable_state);
+ saved_cpu_idle_disable_state = NULL;
+}
+
+/*
+ * set_deepest_cpu_idle_state - limit idle state of cpu
+ *
+ * Disables all idle states deeper than the one given in
+ * deepest_state (assuming states with higher number are deeper).
+ *
+ * This is used to reduce the exit from idle latency. Unlike
+ * set_cpu_dma_latency, it can disable idle states per cpu.
+ *
+ * Return: idle state count on success, negative on error
+ */
+int set_deepest_cpu_idle_state(unsigned int cpu, unsigned int deepest_state)
+{
+ unsigned int nr_states;
+ unsigned int state;
+ int result;
+
+ nr_states = cpuidle_state_count(cpu);
+
+ for (state = deepest_state + 1; state < nr_states; state++) {
+ result = cpuidle_state_disable(cpu, state, 1);
+ if (result < 0)
+ return result;
+ }
+
+ return nr_states;
+}
+#endif /* HAVE_LIBCPUPOWER_SUPPORT */
+
#define _STR(x) #x
#define STR(x) _STR(x)
diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h
index d44513e6c66a..e439db7fc848 100644
--- a/tools/tracing/rtla/src/utils.h
+++ b/tools/tracing/rtla/src/utils.h
@@ -64,6 +64,19 @@ int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr);
int set_comm_cgroup(const char *comm_prefix, const char *cgroup);
int set_pid_cgroup(pid_t pid, const char *cgroup);
int set_cpu_dma_latency(int32_t latency);
+#ifdef HAVE_LIBCPUPOWER_SUPPORT
+int save_cpu_idle_disable_state(unsigned int cpu);
+int restore_cpu_idle_disable_state(unsigned int cpu);
+void free_cpu_idle_disable_states(void);
+int set_deepest_cpu_idle_state(unsigned int cpu, unsigned int state);
+static inline int have_libcpupower_support(void) { return 1; }
+#else
+static inline int save_cpu_idle_disable_state(unsigned int cpu) { return -1; }
+static inline int restore_cpu_idle_disable_state(unsigned int cpu) { return -1; }
+static inline void free_cpu_idle_disable_states(void) { }
+static inline int set_deepest_cpu_idle_state(unsigned int cpu, unsigned int state) { return -1; }
+static inline int have_libcpupower_support(void) { return 0; }
+#endif /* HAVE_LIBCPUPOWER_SUPPORT */
int auto_house_keeping(cpu_set_t *monitored_cpus);
#define ns_to_usf(x) (((double)x/1000))
--
2.46.0
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