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[PATCH v2 0/2] trace-cmd record: add --cpu-list option

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  [PATCH v2 0/2] trace-cmd record: add --cpu-list option Luiz Capitulino <lcapitulino@redhat.com> - 2016-11-22 21:30 +0100
    [PATCH 1/2] trace-cmd record: refactor set_mask() Luiz Capitulino <lcapitulino@redhat.com> - 2016-11-22 21:30 +0100
    [PATCH 2/2] trace-cmd record: add --cpu-list option Luiz Capitulino <lcapitulino@redhat.com> - 2016-11-22 21:30 +0100

#1527894 — [PATCH v2 0/2] trace-cmd record: add --cpu-list option

This series adds support for a --cpu-list option, which is
much more human friendly than -M:

  # trace-cmd record --cpu-list 1,4,10-15 [...]

The first patch is a small refectoring needed to
make --cpu-list support fit nicely. The second patch
adds the new option.

v2
--

- Use the CPU_SET() API instead of cpu.h, which
  makes the cpumask dynamic and avoid various bugs
- Small cleanups and renamings

Luiz Capitulino (2):
  trace-cmd record: refactor set_mask()
  trace-cmd record: add --cpu-list option

 Documentation/trace-cmd-record.1.txt |   4 +
 trace-local.h                        |   2 +-
 trace-record.c                       | 258 ++++++++++++++++++++++++++++++++---
 3 files changed, 245 insertions(+), 19 deletions(-)

-- 
2.5.5

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#1527901 — [PATCH 1/2] trace-cmd record: refactor set_mask()

This commit makes set_mask() more specialized: all
it does now is to write the cpumask to tracing_cpumask.
The handling of "-M -1" is now done by the newly
added alloc_mask_from_hex().

Also, uneeded checks are dropped and
buffer_instance->cpumask points to dynamic memory.

This work is a preparation for supporting the
"--cpu-list" option in the next commit.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 trace-local.h  |  2 +-
 trace-record.c | 54 ++++++++++++++++++++++++++++++++++--------------------
 2 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/trace-local.h b/trace-local.h
index 62363d0..0ac39bf 100644
--- a/trace-local.h
+++ b/trace-local.h
@@ -143,7 +143,7 @@ struct func_list {
 struct buffer_instance {
 	struct buffer_instance	*next;
 	const char		*name;
-	const char		*cpumask;
+	char			*cpumask;
 	struct event_list	*events;
 	struct event_list	**event_next;
 
diff --git a/trace-record.c b/trace-record.c
index 22b6835..0f1f2c4 100644
--- a/trace-record.c
+++ b/trace-record.c
@@ -69,6 +69,8 @@ enum trace_type {
 	TRACE_TYPE_PROFILE	= (1 << 4) | TRACE_TYPE_STREAM,
 };
 
+#define CPUMASK_STR_MAX 4096 /* Don't expect more than 32768 CPUS */
+
 static int rt_prio;
 
 static int keep;
@@ -2078,27 +2080,24 @@ static void update_pid_event_filters(struct buffer_instance *instance)
 	update_event_filters(instance);
 }
 
-static void set_mask(struct buffer_instance *instance)
-{
-	const char *mask = instance->cpumask;
-	struct stat st;
-	char cpumask[4096]; /* Don't expect more than 32768 CPUS */
-	char *path;
-	int fd;
-	int ret;
 
-	if (!mask)
-		return;
+static char *alloc_mask_from_hex(const char *str)
+{
+	char *cpumask;
 
-	if (strcmp(mask, "-1") == 0) {
+	if (strcmp(str, "-1") == 0) {
 		/* set all CPUs */
 		int bytes = (cpu_count + 7) / 8;
 		int last = cpu_count % 8;
 		int i;
 
-		if (bytes > 4095) {
+		cpumask = malloc(CPUMASK_STR_MAX);
+		if (!cpumask)
+			die("can't allocate cpumask");
+
+		if (bytes > (CPUMASK_STR_MAX-1)) {
 			warning("cpumask can't handle more than 32768 CPUS!");
-			bytes = 4095;
+			bytes = CPUMASK_STR_MAX-1;
 		}
 
 		sprintf(cpumask, "%x", (1 << last) - 1);
@@ -2107,18 +2106,32 @@ static void set_mask(struct buffer_instance *instance)
 			cpumask[i] = 'f';
 
 		cpumask[i+1] = 0;
-
-		mask = cpumask;
+	} else {
+		cpumask = strdup(str);
+		if (!cpumask)
+			die("can't allocate cpumask");
 	}
 
+	return cpumask;
+}
+
+static void set_mask(struct buffer_instance *instance)
+{
+	struct stat st;
+	char *path;
+	int fd;
+	int ret;
+
+	if (!instance->cpumask)
+		return;
+
 	path = get_instance_file(instance, "tracing_cpumask");
 	if (!path)
 		die("could not allocate path");
 
 	ret = stat(path, &st);
 	if (ret < 0) {
-		if (mask)
-			warning("%s not found", path);
+		warning("%s not found", path);
 		goto out;
 	}
 
@@ -2126,12 +2139,13 @@ static void set_mask(struct buffer_instance *instance)
 	if (fd < 0)
 		die("could not open %s\n", path);
 
-	if (mask)
-		write(fd, mask, strlen(mask));
+	write(fd, instance->cpumask, strlen(instance->cpumask));
 	
 	close(fd);
  out:
 	tracecmd_put_tracing_file(path);
+	free(instance->cpumask);
+	instance->cpumask = NULL;
 }
 
 static void enable_events(struct buffer_instance *instance)
@@ -4530,7 +4544,7 @@ void trace_record (int argc, char **argv)
 			max_kb = atoi(optarg);
 			break;
 		case 'M':
-			instance->cpumask = optarg;
+			instance->cpumask = alloc_mask_from_hex(optarg);
 			break;
 		case 't':
 			if (extract)
-- 
2.5.5

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#1527908 — [PATCH 2/2] trace-cmd record: add --cpu-list option

With --cpu-list you can do:

  # trace-cmd record --cpu-list 1,4,10-15 [...]

Which is much more human friendly than -M.

Support for --cpu-list is implemented by dynamically
allocating a cpu_set_t object and setting the parsed
CPUs. Using the CPU_SET API allows for more robost
error detection.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 Documentation/trace-cmd-record.1.txt |   4 +
 trace-record.c                       | 208 +++++++++++++++++++++++++++++++++++
 2 files changed, 212 insertions(+)

diff --git a/Documentation/trace-cmd-record.1.txt b/Documentation/trace-cmd-record.1.txt
index b80520e..d7e806a 100644
--- a/Documentation/trace-cmd-record.1.txt
+++ b/Documentation/trace-cmd-record.1.txt
@@ -304,6 +304,10 @@ OPTIONS
     executed will not be changed. This is useful if you want to monitor the
     output of the command being executed, but not see the output from trace-cmd.
 
+*--cpu-list list*::
+    List of CPUs to be traced. The "list" argument can be comma separated
+    (eg. 1,2,4,5), a range (eg. 1-10) or a mix of the two (eg. 1,2,10-15).
+
 EXAMPLES
 --------
 
diff --git a/trace-record.c b/trace-record.c
index 0f1f2c4..49d76db 100644
--- a/trace-record.c
+++ b/trace-record.c
@@ -23,6 +23,7 @@
 #include <string.h>
 #include <stdarg.h>
 #include <getopt.h>
+#include <limits.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/time.h>
@@ -2080,6 +2081,208 @@ static void update_pid_event_filters(struct buffer_instance *instance)
 	update_event_filters(instance);
 }
 
+struct cpuset {
+	int nr_cpus;
+	size_t size;
+	cpu_set_t *set;
+};
+
+static void set_cpu(int cpu, struct cpuset *set)
+{
+	if (cpu < 0 || cpu > set->nr_cpus - 1)
+		die("invalid cpu in range");
+	CPU_SET_S(cpu, set->size, set->set);
+}
+
+static int read_cpu_nr(const char *str, int *ret)
+{
+	char *endptr;
+	int val;
+
+	errno = 0;
+	val = strtol(str, &endptr, 10);
+
+	if ((errno == ERANGE && (val == LONG_MAX || val == LONG_MIN))
+			|| (errno != 0 && val == 0))
+				return -1;
+
+	if (endptr == str)
+		return -1;
+
+	if (*endptr != '\0')
+		return -1;
+
+	*ret = val;
+	return 0;
+}
+
+static int parse_single_cpu(const char *str, struct cpuset *set)
+{
+	int cpu, err;
+
+	err = read_cpu_nr(str, &cpu);
+	if (err)
+		return -1;
+
+	set_cpu(cpu, set);
+	return 0;
+}
+
+static int parse_range_one(char *str, char **saveptr)
+{
+	int err, cpu;
+	char *p;
+
+	p = strtok_r(str, "-", saveptr);
+	if (!p)
+		return -1;
+
+	err = read_cpu_nr(p, &cpu);
+	if (err)
+		return -1;
+
+	return cpu;
+}
+
+static int parse_range(const char *str, int *begin, int *end)
+{
+	char *saveptr, *range;
+	int ret;
+
+	range = strdup(str);
+	if (!range)
+		return -1;
+
+	ret = parse_range_one(range, &saveptr);
+	if (ret < 0)
+		goto out;
+	*begin = ret;
+
+	ret = parse_range_one(NULL, &saveptr);
+	if (ret < 0)
+		goto out;
+	*end = ret;
+
+out:
+	free(range);
+	return ret < 0 ? -1 : 0;
+}
+
+static int parse_cpu_range(const char *str, struct cpuset *set)
+{
+	int i, ret, begin, end;
+
+	ret = parse_range(str, &begin, &end);
+	if (ret < 0 || begin > end)
+		return -1;
+
+	for (i = begin; i <= end; i++)
+		set_cpu(i, set);
+
+	return 0;
+}
+
+static int has_range(const char *str)
+{
+	return strchr(str, '-') != NULL;
+}
+
+static int parse_cpu_list(const char *cpu_list, struct cpuset *set)
+{
+	char *saveptr, *str, *p;
+	int err = 0;
+
+	str = strdup(cpu_list);
+	if (!str)
+		return -1;
+
+	p = strtok_r(str, ",", &saveptr);
+	while (p) {
+		if (has_range(p))
+			err = parse_cpu_range(p, set);
+		else
+			err = parse_single_cpu(p, set);
+		if (err)
+			goto out;
+		p = strtok_r(NULL, ",", &saveptr);
+	}
+
+out:
+	free(str);
+	return err;
+}
+
+static int val_to_char(int v)
+{
+	if (v >= 0 && v < 10)
+		return '0' + v;
+	else if (v >= 10 && v < 16)
+		return ('a' - 10) + v;
+	else
+		return -1;
+}
+
+/* From util-linux */
+static char *cpu_set_to_str(char *str, size_t len, struct cpuset *set)
+{
+	char *ptr = str;
+	char *ret = NULL;
+	int cpu;
+
+	for (cpu = (8 * set->size) - 4; cpu >= 0; cpu -= 4) {
+		char val = 0;
+
+		if (len == (size_t) (ptr - str))
+			break;
+
+		if (CPU_ISSET_S(cpu, set->size, set->set))
+			val |= 1;
+		if (CPU_ISSET_S(cpu + 1, set->size, set->set))
+			val |= 2;
+		if (CPU_ISSET_S(cpu + 2, set->size, set->set))
+			val |= 4;
+		if (CPU_ISSET_S(cpu + 3, set->size, set->set))
+			val |= 8;
+
+		if (!ret && val)
+			ret = ptr;
+		*ptr++ = val_to_char(val);
+	}
+
+	*ptr = '\0';
+	return ret ? ret : ptr - 1;
+}
+
+static char *alloc_mask_from_list(const char *cpu_list)
+{
+	struct cpuset set;
+	char *str;
+	int ret;
+
+	set.nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+	if (set.nr_cpus < 0)
+		die("can't get number of processors\n");
+
+	set.set = CPU_ALLOC(set.nr_cpus);
+	if (!set.set)
+		die("can't allocate cpu_set\n");
+
+	set.size = CPU_ALLOC_SIZE(set.nr_cpus);
+	CPU_ZERO_S(set.size, set.set);
+
+	ret = parse_cpu_list(cpu_list, &set);
+	if (ret < 0)
+		die("invalid cpu list specified");
+
+	str = malloc(CPUMASK_STR_MAX);
+	if (!str)
+		die("can't allocate memory\n");
+
+	cpu_set_to_str(str, CPUMASK_STR_MAX, &set);
+	CPU_FREE(set.set);
+
+	return str;
+}
 
 static char *alloc_mask_from_hex(const char *str)
 {
@@ -4137,6 +4340,7 @@ enum {
 	OPT_nosplice		= 253,
 	OPT_funcstack		= 254,
 	OPT_date		= 255,
+	OPT_cpulist			= 256,
 };
 
 void trace_record (int argc, char **argv)
@@ -4338,6 +4542,7 @@ void trace_record (int argc, char **argv)
 			{"stderr", no_argument, NULL, OPT_stderr},
 			{"by-comm", no_argument, NULL, OPT_bycomm},
 			{"ts-offset", required_argument, NULL, OPT_tsoffset},
+			{"cpu-list", required_argument, NULL, OPT_cpulist},
 			{"max-graph-depth", required_argument, NULL, OPT_max_graph_depth},
 			{"debug", no_argument, NULL, OPT_debug},
 			{"help", no_argument, NULL, '?'},
@@ -4546,6 +4751,9 @@ void trace_record (int argc, char **argv)
 		case 'M':
 			instance->cpumask = alloc_mask_from_hex(optarg);
 			break;
+		case OPT_cpulist:
+			instance->cpumask = alloc_mask_from_list(optarg);
+			break;
 		case 't':
 			if (extract)
 				topt = 1; /* Extract top instance also */
-- 
2.5.5

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