Date:   Sat, 3 Mar 2018 09:51:05 +0100
From:   "Dr. Thomas Orgis" <thomas.orgis@...-hamburg.de>
To:     <linux-kernel@...r.kernel.org>
Cc:     Balbir Singh <bsingharora@...il.com>
Subject: [RFC] [PATCH] taskstats: introduce verison 9 with executable file
 info: empty device ID

Hi,

this is a request for comments/help for a little patch I am working on.
It works to give me an inode for the executable file of an existing
task via taskstats, but I fail to get a device ID for that to be able
to then look for the correct filesystem in userspace. I am not sure if
that information is still supposed to be present at the time the stats
are produced. Basically, I want an efficient way to get the
path /proc/$pid/exe points to at process exit. I really would like to
not bother with individual tasks but only task groups (userspace
processes), but that seems to be tricky in taskstats, not being able to
tell a single-threaded process from a single thread of a multi-threaded
process … and also the tgid stats miss anything but the delay
accounting fields right now. My application in HPC just wants global
stats about wall-/cputime and memory use in a cluster, accounted for by
executable path, which encodes the used scientific software package and
version in our setup.

The one big hurdle I have at the moment is that I'm a n00b at kernel
development and just am taking gueses from the code I see. So far I
think I am accessing the correct struct member for the device ID, but
perhaps at the wrong time.

Also, I am open for suggestions for some better way of identifying the
executable. Instead of/in addition to the device ID, I would be
interested in the fsid (as given by `stat -c %i`) , for example. This
is stable for an NFS filesystem mounted on multiple nodes, where each
node has its own major:minor made up for the mount. But then, the
overlayfs for / on each netbooted node has a different fsid, while the
major:minor stays the same. So both would be good, I guess. Or a
filesystem UUID.

This is my commit/patch so far:

>From 9ed4c720448ff8a4308cfb14b70de0ee7d30c279 Mon Sep 17 00:00:00 2001
From: Thomas Orgis <thomas.orgis@...-hamburg.de>
Date: Sat, 3 Mar 2018 08:36:43 +0100
Subject: [PATCH] taskstats: introduce verison 9 with executable file info

This adds fields to the taskstats struct that give device and inode info
for the executable file associated with the process as a safer way
to get that than polling /proc/$pid/exe before a process ends.

The getdelay example program is accompanied by a variant that
just prints a stream of exiting tasks with the added info.

The idea is to be able to collect global statistics about use of certain
programs installed on a system by associating process/task stats with
an absolute executable path. The command field is unsuitable as it
does not distinguish between /foo/bar/v1.2.3/bin/bar_exe and
/foo/bar/v2.3.4/bin/bar_exe and is generally rather arbitrary.

I would like to just get the path communicated to userspace,
but I presume the growth of the struct by PATH_MAX bytes would
not be welcomed.

TODO: Device number is always zero. I am using it wrong.
      Is it too late to get that info at task exit?

Signed-off-by: Thomas Orgis <thomas.orgis@...-hamburg.de>
---
 include/uapi/linux/taskstats.h |  20 +-
 kernel/taskstats.c             |  17 ++
 tools/accounting/.gitignore    |   1 +
 tools/accounting/procacct.c    | 427 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 464 insertions(+), 1 deletion(-)
 create mode 100644 tools/accounting/procacct.c

diff --git a/include/uapi/linux/taskstats.h b/include/uapi/linux/taskstats.h
index b7aa7bb2349f..56b4a67f035c 100644
--- a/include/uapi/linux/taskstats.h
+++ b/include/uapi/linux/taskstats.h
@@ -34,7 +34,7 @@
  */
 
 
-#define TASKSTATS_VERSION	8
+#define TASKSTATS_VERSION	9
 #define TS_COMM_LEN		32	/* should be >= TASK_COMM_LEN
 					 * in linux/sched.h */
 
@@ -164,6 +164,24 @@ struct taskstats {
 	/* Delay waiting for memory reclaim */
 	__u64	freepages_count;
 	__u64	freepages_delay_total;
+
+	/*
+	 * Version 9:
+	 * Extra fields detailing executable file (/proc/$pid/exe).
+	 * Values are both zero if there is no executable file
+	 * Chose 64 bit for both to keep alignment. Only 32 bit expected
+	 * for device, while userspace will usually only use 16 anyway.
+	 * The client application is supposed to translate that to a
+	 * file path itself, with knowledge about possible failure
+	 * modes (changes in mounts, filesystem operations).
+	 * Communicating the path from the kernel's view would mean
+	 * adding PATH_MAX bytes to this struct and more work.
+	 * I guess we do not want that. It would be convenient, though.
+	 */
+	__u64	ac_exe_dev;	/* device ID */
+	__u64	ac_exe_inode;	/* inode number */
+	/* Version 9 ends here. */
+
 };
 
 
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 4e62a4a8fa91..0f589acd95cd 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -166,6 +166,20 @@ static void send_cpu_listeners(struct sk_buff *skb,
 	up_write(&listeners->sem);
 }
 
+static void exe_add_tsk(struct taskstats *stats, struct task_struct *tsk)
+{
+	/* No idea if I'm allowed to access that here, now. */
+	struct file *exe_file = get_task_exe_file(tsk);
+	if (exe_file) {
+		stats->ac_exe_dev = new_encode_dev(exe_file->f_inode->i_rdev);
+		stats->ac_exe_inode = exe_file->f_inode->i_ino;
+		fput(exe_file);
+	} else {
+		stats->ac_exe_dev = 0;
+		stats->ac_exe_inode = 0;
+	}
+}
+
 static void fill_stats(struct user_namespace *user_ns,
 		       struct pid_namespace *pid_ns,
 		       struct task_struct *tsk, struct taskstats *stats)
@@ -188,6 +202,9 @@ static void fill_stats(struct user_namespace *user_ns,
 
 	/* fill in extended acct fields */
 	xacct_add_tsk(stats, tsk);
+
+	/* add executable info */
+	exe_add_tsk(stats, tsk);
 }
 
 static int fill_stats_for_pid(pid_t pid, struct taskstats *stats)
diff --git a/tools/accounting/.gitignore b/tools/accounting/.gitignore
index 86485203c4ae..6a420bc8a63d 100644
--- a/tools/accounting/.gitignore
+++ b/tools/accounting/.gitignore
@@ -1 +1,2 @@
 getdelays
+procacct
diff --git a/tools/accounting/procacct.c b/tools/accounting/procacct.c
new file mode 100644
index 000000000000..0044416c689f
--- /dev/null
+++ b/tools/accounting/procacct.c
@@ -0,0 +1,427 @@
+/* procacct.c
+ *
+ * Utility to get a stream of task (TODO: process/task group) statistics
+ * as they exit including information on the executable file
+ * Derived from getdelays.c, hence the list of initial authors:
+ *
+ * Copyright (C) Shailabh Nagar, IBM Corp. 2005
+ * Copyright (C) Balbir Singh, IBM Corp. 2006
+ * Copyright (c) Jay Lan, SGI. 2006
+ * Copyright (C) Thomas Orgis, Univ. of Hamburg 2018
+ *
+ * Compile with
+ *	gcc -I/usr/src/linux/include procacct.c -o procacct
+ *
+ * I intended to only count processes (tgid stats), but that
+ * gives empty values for the stats I am interested in. And also
+ * I am missing all single-threaded processes. There was
+ * a patch posted ages ago that would have added the accounting
+ * fields in the aggregation ... but did not make it, apparently.
+ * Linux kernel folks are interested in more detailed stuff
+ * that says things about the kernel's performance itself, while
+ * I want a reliable way to add up the compute/memory resources used
+ * by certain processes.
+ *
+ * So, this reports task stats only, hoping that a consumer of the
+ * data will sum up the threads sharing a common executable.
+ * Counters for program instances do not make sense as long as
+ * I cannot really tell processes and mere threads apart.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+#include <poll.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <signal.h>
+
+#include <linux/genetlink.h>
+#include <linux/taskstats.h>
+#include <linux/kdev_t.h>
+
+/*
+ * Generic macros for dealing with netlink sockets. Might be duplicated
+ * elsewhere. It is recommended that commercial grade applications use
+ * libnl or libnetlink and use the interfaces provided by the library
+ */
+#define GENLMSG_DATA(glh)	((void *)(NLMSG_DATA(glh) + GENL_HDRLEN))
+#define GENLMSG_PAYLOAD(glh)	(NLMSG_PAYLOAD(glh, 0) - GENL_HDRLEN)
+#define NLA_DATA(na)		((void *)((char*)(na) + NLA_HDRLEN))
+#define NLA_PAYLOAD(len)	(len - NLA_HDRLEN)
+
+#define err(code, fmt, arg...)			\
+	do {					\
+		fprintf(stderr, fmt, ##arg);	\
+		exit(code);			\
+	} while (0)
+
+int done;
+int rcvbufsz;
+char name[100];
+int dbg;
+int print_delays;
+int print_io_accounting;
+int print_task_context_switch_counts;
+
+#define PRINTF(fmt, arg...) {			\
+	    if (dbg) {				\
+		printf(fmt, ##arg);		\
+	    }					\
+	}
+
+/* Maximum size of response requested or message sent */
+#define MAX_MSG_SIZE	1024
+/* Maximum number of cpus expected to be specified in a cpumask */
+#define MAX_CPUS	32
+
+struct msgtemplate {
+	struct nlmsghdr n;
+	struct genlmsghdr g;
+	char buf[MAX_MSG_SIZE];
+};
+
+char cpumask[100+6*MAX_CPUS];
+
+static void usage(void)
+{
+	fprintf(stderr, "getdelays [-dilv] [-w logfile] [-r bufsize] "
+			"[-m cpumask] [-t tgid] [-p pid]\n");
+	fprintf(stderr, "  -d: print delayacct stats\n");
+	fprintf(stderr, "  -i: print IO accounting (works only with -p)\n");
+	fprintf(stderr, "  -l: listen forever\n");
+	fprintf(stderr, "  -v: debug on\n");
+	fprintf(stderr, "  -C: container path\n");
+}
+
+/*
+ * Create a raw netlink socket and bind
+ */
+static int create_nl_socket(int protocol)
+{
+	int fd;
+	struct sockaddr_nl local;
+
+	fd = socket(AF_NETLINK, SOCK_RAW, protocol);
+	if (fd < 0)
+		return -1;
+
+	if (rcvbufsz)
+		if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF,
+				&rcvbufsz, sizeof(rcvbufsz)) < 0) {
+			fprintf(stderr, "Unable to set socket rcv buf size to %d\n",
+				rcvbufsz);
+			goto error;
+		}
+
+	memset(&local, 0, sizeof(local));
+	local.nl_family = AF_NETLINK;
+
+	if (bind(fd, (struct sockaddr *) &local, sizeof(local)) < 0)
+		goto error;
+
+	return fd;
+error:
+	close(fd);
+	return -1;
+}
+
+
+static int send_cmd(int sd, __u16 nlmsg_type, __u32 nlmsg_pid,
+	     __u8 genl_cmd, __u16 nla_type,
+	     void *nla_data, int nla_len)
+{
+	struct nlattr *na;
+	struct sockaddr_nl nladdr;
+	int r, buflen;
+	char *buf;
+
+	struct msgtemplate msg;
+
+	msg.n.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
+	msg.n.nlmsg_type = nlmsg_type;
+	msg.n.nlmsg_flags = NLM_F_REQUEST;
+	msg.n.nlmsg_seq = 0;
+	msg.n.nlmsg_pid = nlmsg_pid;
+	msg.g.cmd = genl_cmd;
+	msg.g.version = 0x1;
+	na = (struct nlattr *) GENLMSG_DATA(&msg);
+	na->nla_type = nla_type;
+	na->nla_len = nla_len + 1 + NLA_HDRLEN;
+	memcpy(NLA_DATA(na), nla_data, nla_len);
+	msg.n.nlmsg_len += NLMSG_ALIGN(na->nla_len);
+
+	buf = (char *) &msg;
+	buflen = msg.n.nlmsg_len ;
+	memset(&nladdr, 0, sizeof(nladdr));
+	nladdr.nl_family = AF_NETLINK;
+	while ((r = sendto(sd, buf, buflen, 0, (struct sockaddr *) &nladdr,
+			   sizeof(nladdr))) < buflen) {
+		if (r > 0) {
+			buf += r;
+			buflen -= r;
+		} else if (errno != EAGAIN)
+			return -1;
+	}
+	return 0;
+}
+
+
+/*
+ * Probe the controller in genetlink to find the family id
+ * for the TASKSTATS family
+ */
+static int get_family_id(int sd)
+{
+	struct {
+		struct nlmsghdr n;
+		struct genlmsghdr g;
+		char buf[256];
+	} ans;
+
+	int id = 0, rc;
+	struct nlattr *na;
+	int rep_len;
+
+	strcpy(name, TASKSTATS_GENL_NAME);
+	rc = send_cmd(sd, GENL_ID_CTRL, getpid(), CTRL_CMD_GETFAMILY,
+			CTRL_ATTR_FAMILY_NAME, (void *)name,
+			strlen(TASKSTATS_GENL_NAME)+1);
+	if (rc < 0)
+		return 0;	/* sendto() failure? */
+
+	rep_len = recv(sd, &ans, sizeof(ans), 0);
+	if (ans.n.nlmsg_type == NLMSG_ERROR ||
+	    (rep_len < 0) || !NLMSG_OK((&ans.n), rep_len))
+		return 0;
+
+	na = (struct nlattr *) GENLMSG_DATA(&ans);
+	na = (struct nlattr *) ((char *) na + NLA_ALIGN(na->nla_len));
+	if (na->nla_type == CTRL_ATTR_FAMILY_ID) {
+		id = *(__u16 *) NLA_DATA(na);
+	}
+	return id;
+}
+
+#define average_ms(t, c) (t / 1000000ULL / (c ? c : 1))
+
+static void print_procacct(struct taskstats *t)
+{
+	printf("pid=%lu uid=%lu wall=%llu cpu=%llu vmpeak=%llu rsspeak=%llu dev=%llu:%llu inode=%llu\n"
+	,	(unsigned long)t->ac_pid
+	,	(unsigned long)t->ac_uid
+	,	(unsigned long long)t->ac_etime
+	,	(unsigned long long)(t->ac_utime+t->ac_stime)
+	,	(unsigned long long)t->hiwater_vm
+	,	(unsigned long long)t->hiwater_rss
+	,	(unsigned long)(t->version >= 9 ? MAJOR(t->ac_exe_dev) : 0)
+	,	(unsigned long)(t->version >= 9 ? MINOR(t->ac_exe_dev) : 0)
+	,	(unsigned long long)(t->version >= 9 ? t->ac_exe_inode : 0)
+	);
+}
+
+int main(int argc, char *argv[])
+{
+	int c, rc, rep_len, aggr_len, len2;
+	int cmd_type = TASKSTATS_CMD_ATTR_UNSPEC;
+	__u16 id;
+	__u32 mypid;
+
+	struct nlattr *na;
+	int nl_sd = -1;
+	int len = 0;
+	pid_t tid = 0;
+	pid_t rtid = 0;
+
+	int fd = 0;
+	int count = 0;
+	int write_file = 0;
+	int maskset = 0;
+	char *logfile = NULL;
+	int loop = 1;
+	int containerset = 0;
+	char *containerpath = NULL;
+	int cfd = 0;
+	int forking = 0;
+	sigset_t sigset;
+
+	struct msgtemplate msg;
+
+	while (!forking) {
+		c = getopt(argc, argv, "m:vr:");
+		if (c < 0)
+			break;
+
+		switch (c) {
+		case 'w':
+			logfile = strdup(optarg);
+			printf("write to file %s\n", logfile);
+			write_file = 1;
+			break;
+		case 'r':
+			rcvbufsz = atoi(optarg);
+			printf("receive buf size %d\n", rcvbufsz);
+			if (rcvbufsz < 0)
+				err(1, "Invalid rcv buf size\n");
+			break;
+		case 'm':
+			strncpy(cpumask, optarg, sizeof(cpumask));
+			cpumask[sizeof(cpumask) - 1] = '\0';
+			maskset = 1;
+			break;
+		case 'v':
+			printf("debug on\n");
+			dbg = 1;
+			break;
+		default:
+			usage();
+			exit(-1);
+		}
+	}
+	if(!maskset)
+	{
+		maskset = 1;
+		strncpy(cpumask, "1", sizeof(cpumask));
+		cpumask[sizeof(cpumask) - 1] = '\0';
+	}
+	printf("cpumask %s maskset %d\n", cpumask, maskset);
+
+	if (write_file) {
+		fd = open(logfile, O_WRONLY | O_CREAT | O_TRUNC,
+			  S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+		if (fd == -1) {
+			perror("Cannot open output file\n");
+			exit(1);
+		}
+	}
+
+	nl_sd = create_nl_socket(NETLINK_GENERIC);
+	if (nl_sd < 0)
+		err(1, "error creating Netlink socket\n");
+
+
+	mypid = getpid();
+	id = get_family_id(nl_sd);
+	if (!id) {
+		fprintf(stderr, "Error getting family id, errno %d\n", errno);
+		goto err;
+	}
+	PRINTF("family id %d\n", id);
+
+	if (maskset) {
+		rc = send_cmd(nl_sd, id, mypid, TASKSTATS_CMD_GET,
+			      TASKSTATS_CMD_ATTR_REGISTER_CPUMASK,
+			      &cpumask, strlen(cpumask) + 1);
+		PRINTF("Sent register cpumask, retval %d\n", rc);
+		if (rc < 0) {
+			fprintf(stderr, "error sending register cpumask\n");
+			goto err;
+		}
+	}
+
+	do {
+		rep_len = recv(nl_sd, &msg, sizeof(msg), 0);
+		PRINTF("received %d bytes\n", rep_len);
+
+		if (rep_len < 0) {
+			fprintf(stderr, "nonfatal reply error: errno %d\n",
+				errno);
+			continue;
+		}
+		if (msg.n.nlmsg_type == NLMSG_ERROR ||
+		    !NLMSG_OK((&msg.n), rep_len)) {
+			struct nlmsgerr *err = NLMSG_DATA(&msg);
+			fprintf(stderr, "fatal reply error,  errno %d\n",
+				err->error);
+			goto done;
+		}
+
+		PRINTF("nlmsghdr size=%zu, nlmsg_len=%d, rep_len=%d\n",
+		       sizeof(struct nlmsghdr), msg.n.nlmsg_len, rep_len);
+
+
+		rep_len = GENLMSG_PAYLOAD(&msg.n);
+
+		na = (struct nlattr *) GENLMSG_DATA(&msg);
+		len = 0;
+		while (len < rep_len) {
+			len += NLA_ALIGN(na->nla_len);
+			int mother = na->nla_type;
+			PRINTF("mother=%i\n", mother);
+			switch (na->nla_type) {
+			case TASKSTATS_TYPE_AGGR_PID:
+				/* Fall through */
+			case TASKSTATS_TYPE_AGGR_TGID:
+				/* Fall through */
+				aggr_len = NLA_PAYLOAD(na->nla_len);
+				len2 = 0;
+				/* For nested attributes, na follows */
+				na = (struct nlattr *) NLA_DATA(na);
+				done = 0;
+				while (len2 < aggr_len) {
+					switch (na->nla_type) {
+					case TASKSTATS_TYPE_PID:
+						rtid = *(int *) NLA_DATA(na);
+						PRINTF("PID\t%d\n", rtid);
+						break;
+					case TASKSTATS_TYPE_TGID:
+						rtid = *(int *) NLA_DATA(na);
+						PRINTF("TGID\t%d\n", rtid);
+						break;
+					case TASKSTATS_TYPE_STATS:
+						count++;
+						if(mother == TASKSTATS_TYPE_AGGR_PID)
+							print_procacct((struct taskstats *) NLA_DATA(na));
+						if (fd) {
+							if (write(fd, NLA_DATA(na), na->nla_len) < 0) {
+								err(1,"write error\n");
+							}
+						}
+						if (!loop)
+							goto done;
+						break;
+					case TASKSTATS_TYPE_NULL:
+						break;
+					default:
+						fprintf(stderr, "Unknown nested"
+							" nla_type %d\n",
+							na->nla_type);
+						break;
+					}
+					len2 += NLA_ALIGN(na->nla_len);
+					na = (struct nlattr *)((char *)na +
+							       NLA_ALIGN(na->nla_len));
+				}
+				break;
+
+			default:
+				fprintf(stderr, "Unexpected nla_type %d\n",
+					na->nla_type);
+			case TASKSTATS_TYPE_NULL:
+				break;
+			}
+			na = (struct nlattr *) (GENLMSG_DATA(&msg) + len);
+		}
+	} while (loop);
+done:
+	if (maskset) {
+		rc = send_cmd(nl_sd, id, mypid, TASKSTATS_CMD_GET,
+			      TASKSTATS_CMD_ATTR_DEREGISTER_CPUMASK,
+			      &cpumask, strlen(cpumask) + 1);
+		printf("Sent deregister mask, retval %d\n", rc);
+		if (rc < 0)
+			err(rc, "error sending deregister cpumask\n");
+	}
+err:
+	close(nl_sd);
+	if (fd)
+		close(fd);
+	if (cfd)
+		close(cfd);
+	return 0;
+}
-- 
2.15.1




-- 
Dr. Thomas Orgis
HPC @ Universität Hamburg

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