bpftune: add bpftune -q <query> client/server to allow local queries

create server for bpftune requests using ephemeral port,
port # stored locally in /var/run/bpftune/server-port.
Requests supported are

list: list requests supported
tuners: show tuners,states of each
tunables: show tunables
summary: summary of changes made

example:

$ /sbin/bpftune -q summary
Summary of changes made across all tuners:
Summary: scenario 'need to increase TCP buffer size(s)' occurred 2 times for tunable 'net.ipv4.tcp_wmem' in global ns. Need to increase buffer size(s) to maximize throughput
sysctl 'net.ipv4.tcp_wmem' changed from (4096 16384 16384 ) -> (4096 16384 25600 )

Also add query test

Signed-off-by: Alan Maguire <[email protected]>

README.md

@@ -240,6 +240,8 @@ $ sudo bpftune -s
 
 On exit, bpftune will summarize any tuning done.
 
+Queries of bpftune state can be done via `bpftune -q`.
+
 ## Tests
 
 Tests are supplied for each tuner in the tests/ subdirectory.

docs/bpftune.rst

@@ -18,6 +18,8 @@ SYNOPSIS
         { [**-r** | **--learning_rate** ] learning_rate}
         { [**-R** | **--rollback** ]}
         { [**-S** | **--support** ]}
+        { [**-p** | **--port** ] port}
+        { [**-q** | **--query**] query}
 
 DESCRIPTION
 ===========
@@ -85,3 +87,17 @@ OPTIONS
                 to the system.  On exit, bpftune summarizes the changes made
                 and rolls back to the sysctl values that were set prior to
                 bpftune running.
+
+         -p, --port
+
+                TCP port to listen on for queries.  If not specified, use an
+                ephemeral localhost port.
+
+         -q, --query
+
+                Query bpftune.  Supported queries include
+
+                help        - show supported queries
+                summary     - show summary of changes made by tuners
+                tuners      - show loaded tuners and their state
+                tunables    - show supported tunables for loaded tuners

include/bpftune/libbpftune.h

@@ -30,20 +30,24 @@
 #include <string.h>
 #include <syslog.h>
 #include <unistd.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
 #include <sys/socket.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <dirent.h>
 #include <libgen.h>
 #include <linux/types.h>
+#include <pthread.h>
 
 #include <bpftune/bpftune.h>
 
 #include <bpf/bpf.h>
 #include <bpf/libbpf.h>
 
 #define BPFTUNE_RUN_DIR			"/var/run/bpftune"
+#define BPFTUNE_PORT_FILE		BPFTUNE_RUN_DIR	"/server-port"
 #define BPFTUNER_CGROUP_DIR		BPFTUNE_RUN_DIR "/cgroupv2"
 #ifndef BPFTUNER_PREFIX_DIR
 #define BPFTUNER_PREFIX_DIR		"/usr"
@@ -65,19 +69,39 @@
 #define ARRAY_SIZE(arr)			(sizeof(arr) / sizeof((arr)[0])) 
 #endif
 
+#define BPFTUNE_SERVER_MSG_MAX		65536
+
+char *bpftune_state_string[] = {
+	"inactive",
+	"active",
+	"manual",
+	"gone",
+};
+
 /* level for bpftune tunable updates */
 #define BPFTUNE_LOG_LEVEL		LOG_NOTICE
 
+/* write to buffer and log using nextlogfn */
+struct bpftune_log_ctx_buf {
+	void (*nextlogfn)(void *ctx, int level, const char *fmt, va_list args);
+	pthread_t buf_thread;
+	char *buf;
+	size_t buf_off;
+	size_t buf_sz;
+};
+
 int bpftune_log_level(void);
 
 void bpftune_log(int level, const char *fmt, ...);
 
 void bpftune_log_stderr(void *ctx, int level, const char *fmt, va_list args);
 void bpftune_log_syslog(void *ctx, int level, const char *fmt, va_list args);
+void bpftune_log_buf(void *ctx, int level, const char *fmt, va_list args);
 
 void bpftune_set_log(int level,
 		     void (*logfn)(void *ctx, int level, const char *fmt,
-				   va_list args));
+				   va_list args),
+		     void *ctx);
 void bpftune_set_bpf_log(bool log);
 
 void bpftune_log_bpf_err(int err, const char *fmt);
@@ -93,6 +117,13 @@ int bpftune_cgroup_init(const char *cgroup_path);
 const char *bpftune_cgroup_name(void);
 int bpftune_cgroup_fd(void);
 void bpftune_cgroup_fini(void);
+
+int bpftune_server_start(unsigned short port);
+int bpftune_server_port(void);
+void bpftune_server_stop(void);
+int bpftune_server_request(struct sockaddr_in *server, const char *req,
+			   char *buf, size_t buf_sz);
+
 int bpftuner_cgroup_attach(struct bpftuner *tuner, const char *prog_name,
 			   enum bpf_attach_type attach_type);
 void bpftuner_cgroup_detach(struct bpftuner *tuner, const char *prog_name,

src/bpftune.c

@@ -36,11 +36,13 @@
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/resource.h>
+#include <sys/socket.h>
 #include <sys/stat.h>
 #include <dirent.h>
 #include <libgen.h>
 #include <linux/types.h>
 #include <linux/limits.h>
+#include <netinet/in.h>
 #include <pthread.h>
 #include <sys/inotify.h>
 #include <ftw.h>
@@ -75,6 +77,7 @@ static void cleanup(int sig)
 {
 	exiting = true;
 	bpftune_log(LOG_DEBUG, "cleaning up, got signal %d\n", sig);
+	bpftune_server_stop();
 	bpftune_ring_buffer_fini(ring_buffer);
 	if (use_stderr)
 		fflush(stderr);
@@ -239,6 +242,8 @@ void do_help(void)
 		"		     { -L|--legacy}\n"
 		"		     { -h|--help}}\n"
 		"		     { -l|--library_path library_path}\n"
+		"		     { -p|--port port}\n"
+		"		     { -q|--query query}\n"
 		"		     { -r|--learning_rate learning_rate}\n"
 		"		     { -R|--rollback}\n"
 		"		     { -s|--stderr}\n"
@@ -292,6 +297,8 @@ int main(int argc, char *argv[])
 		{ "help",	no_argument,		NULL,	'h' },
 		{ "libdir",	required_argument,	NULL,	'l' },
 		{ "learning_rate", required_argument,	NULL,	'r' },
+		{ "port",	required_argument,	NULL,	'p' },
+		{ "query",	required_argument,	NULL,	'q' },
 		{ "rollback",	no_argument,		NULL,	'R' },
 		{ "stderr", 	no_argument,		NULL,	's' },
 		{ "support",	no_argument,		NULL,	'S' },
@@ -306,12 +313,15 @@ int main(int argc, char *argv[])
 	int log_level = BPFTUNE_LOG_LEVEL;
 	struct sigaction sa = {}, oldsa = {};
 	bool support_only = false;
+	bool client = false;
+	char *query = NULL;
 	int interval = 100;
+	unsigned short port = 0;
 	int err, opt;
 
 	bin_name = argv[0];
 
-	while ((opt = getopt_long(argc, argv, "a:c:dDhl:Lr:RsSV", options, NULL))
+	while ((opt = getopt_long(argc, argv, "a:c:dDhl:Lr:p:q:RsSV", options, NULL))
 		>= 0) {
 		switch (opt) {
 		case 'a':
@@ -347,6 +357,14 @@ int main(int argc, char *argv[])
 				return 1;
 			}
 			break;
+		case 'p':
+			port = (unsigned short)atoi(optarg);
+			break;
+		case 'q':
+			query = optarg;
+			client = true;
+			use_stderr = true;
+			break;
 		case 'R':
 			rollback = true;
 			break;
@@ -367,7 +385,24 @@ int main(int argc, char *argv[])
 		}
 	}
 
-	bpftune_set_log(log_level, use_stderr ? bpftune_log_stderr : bpftune_log_syslog);
+	bpftune_set_log(log_level,
+			use_stderr ? bpftune_log_stderr : bpftune_log_syslog,
+			NULL);
+
+	if (client) {
+		char buf[BPFTUNE_SERVER_MSG_MAX];
+		struct sockaddr_in server;
+
+		memset(&server, 0, sizeof(server));
+		server.sin_family = AF_INET;
+		server.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+		server.sin_port = htons(port);
+
+		err = bpftune_server_request(&server, query, buf, sizeof(buf));
+		if (err == 0)
+			fprintf(stdout, "%s\n", buf);
+		return err;
+	}
 
 	bpftune_set_learning_rate(rate);
 
@@ -382,7 +417,7 @@ int main(int argc, char *argv[])
 		exit(EXIT_FAILURE);
 
 	/* need to setup cgroup prior to probe as probe program uses sysctl */
-	err = mkdir(BPFTUNE_RUN_DIR, 0700);
+	err = mkdir(BPFTUNE_RUN_DIR, 0755);
 	if (err && errno != EEXIST) {
 		bpftune_log(BPFTUNE_LOG_LEVEL, "could not create '%s': %s\n",
 			    BPFTUNE_RUN_DIR, strerror(errno));
@@ -401,6 +436,9 @@ int main(int argc, char *argv[])
 	if (support_only)
 		return 0;
 
+	if (bpftune_server_start(port) != 0)
+		exit(EXIT_FAILURE);
+
 	bpftune_cap_drop();
 
 	err = init(BPFTUNER_LIB_DIR);