Handle offline cpus gracefully

Several parts of idlestat code did not cope with some cpu(s)
being offline. This patch adds information to cpu topology
data structure to record online status. Online-sensitive
parts of the code may query the status using is_cpu_online()
and skip performing activities related to offline cpus.

The following activities are skipped of cpu is offline:
- Trace: Obtaining initial frequency
- Trace: Storing initial frequency
- Trace: Adding pseudo pstate transition 0 Hz to end of trace
- Trace: Storing cpu C-state information
- Tracefile_idlestat: Reading cpu C-state information
- Topology: Mapping "datas" to "topology"

Signed-off-by: Tuukka Tikkanen <idlestat@tic0.net>
Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>

1 files changed, 19 insertions, 8 deletions

diff --git a/idlestat.c b/idlestat.c
index f52bd0b..22a9781 100644
--- a/idlestat.c
+++ b/idlestat.c
@@ -352,7 +352,7 @@ static void release_init_pstates(struct init_pstates *initp)
 	free(initp);
 }
 
-static struct init_pstates *build_init_pstates(void)
+static struct init_pstates *build_init_pstates(struct cpu_topology *topo)
 {
 	struct init_pstates *initp;
 	int nrcpus, cpu;
@@ -378,6 +378,9 @@ static struct init_pstates *build_init_pstates(void)
 		char *fpath;
 		unsigned int *freq = &(freqs[cpu]);
 
+		if (!cpu_is_online(topo, cpu))
+			continue;
+
 		if (asprintf(&fpath, CPUFREQ_CURFREQ_PATH_FORMAT, cpu) < 0) {
 			release_init_pstates(initp);
 			return NULL;
@@ -390,7 +393,8 @@ static struct init_pstates *build_init_pstates(void)
 	return initp;
 }
 
-static void output_pstates(FILE *f, struct init_pstates *initp, int nrcpus,
+static void output_pstates(FILE *f, struct init_pstates *initp,
+				int nrcpus, struct cpu_topology *topo,
 				double ts)
 {
 	int cpu;
@@ -401,7 +405,10 @@ static void output_pstates(FILE *f, struct init_pstates *initp, int nrcpus,
 	ts_usec = (ts - ts_sec) * USEC_PER_SEC;
 
 	for (cpu = 0; cpu < nrcpus; cpu++) {
-		freq = initp? initp->freqs[cpu] : 0;
+		if (!cpu_is_online(topo, cpu))
+			continue;
+
+		freq = initp ? initp->freqs[cpu] : 0;
 		fprintf(f, "%16s-%-5d [%03d] .... %5lu.%06lu: cpu_frequency: "
 			"state=%u cpu_id=%d\n", "idlestat", getpid(), cpu,
 			ts_sec, ts_usec, freq, cpu);
@@ -931,7 +938,8 @@ static void write_cstate_info(FILE *f, char *name, int target)
 	fprintf(f, "\t%d\n", target);
 }
 
-void output_cstate_info(FILE *f, int nrcpus) {
+void output_cstate_info(FILE *f, struct cpu_topology * topo, int nrcpus)
+{
 	struct cpuidle_cstates *cstates;
 	int i, j;
 
@@ -939,6 +947,9 @@ void output_cstate_info(FILE *f, int nrcpus) {
 	assert(!is_err(cstates));
 
 	for (i=0; i < nrcpus; i++) {
+		if (!cpu_is_online(topo, i))
+			continue;
+
 		fprintf(f, "cpuid %d:\n",  i);
 		for (j=0; j < MAXCSTATE ; j++) {
 			write_cstate_info(f, cstates[i].cstate[j].name,
@@ -1281,17 +1292,17 @@ static int idlestat_store(const char *path, double start_ts, double end_ts,
 	output_cpu_topo_info(cpu_topo, f);
 
 	/* output c-states information */
-	output_cstate_info(f, ret);
+	output_cstate_info(f, cpu_topo, ret);
 
 	/* emit initial pstate changes */
 	if (initp)
-		output_pstates(f, initp, initp->nrcpus, start_ts);
+		output_pstates(f, initp, initp->nrcpus, cpu_topo, start_ts);
 
 	ret = idlestat_file_for_each_line(TRACE_FILE, f, store_line);
 
 	/* emit final pstate changes */
 	if (initp)
-		output_pstates(f, NULL, initp->nrcpus, end_ts);
+		output_pstates(f, NULL, initp->nrcpus, cpu_topo, end_ts);
 
 	fclose(f);
 
@@ -1494,7 +1505,7 @@ int main(int argc, char *argv[], char *const envp[])
 		if (get_trace_ts(&start_ts) == -1)
 			goto err_restore_trace_options;
 
-		initp = build_init_pstates();
+		initp = build_init_pstates(cpu_topo);
 
 		/* Start the recording */
 		if (idlestat_trace_enable(true))