Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats

Jay Lan
2006-06-21T19:14:33Z

[-- Attachment #1: Type: text/plain, Size: 4536 bytes --]

Jay Lan wrote:
>Shailabh Nagar wrote:
>
>>Andrew Morton wrote:
>>
>>
>>>You see the problem - if one userspace package wants the tgid-stats and
>>>another concurrently-running one does now, what do we do? Just leave it
>>>enabled and run a bit slower?
>>>
>>>If so, how much slower? Your changelog says some potential users don't
>>>need the tgid-stats, but so what? I assume this patch is a performance
>>>thing? If so, has it been quantified?
>>>
>>>
>>Here are some results from running a simple program (source below) that does
>>10 iterations of creating and then destroying 1000 threads. On the side, another utility
>>kept reading the pid (+tgid if present) stats from exiting tasks.
>>
>>
>
>I ran my testing using the same program posted by Shalilabh attached in his
>posting.
>
>System: SGI a350, a two cpus IA64 machine.
>Kernel: 2.6.17-rc3 + delay-acct-taskstats patch set
> + tgid-disable_patch_shailabh + exit race patch_balbir +
>csa_patch_jlan
>
>I also modified the Decumentation/accounting/getdelay.c:
> - it repeatedly does recv() to retrieve data from kernel
> - instead of using printf() to display data received, i simply write
>it to
> disk as it would be for an accounting daemon. Note that currently
>both the
> BSD (or GNU) accounting and the CSA writes accounting data from kernel.
> As an effort of moving accounting system to userspace, the raw data
>needs
> to be written to a raw file first before further processing.
>
>In Shailabh's testing, he ran his 'mkthreads' 10 iterations of creating and
>distroying 1000 threads. I had to increase my test to 5000 iterations
>in order
>to receive meaningful data: 'mkthreads 1000 5000'.
>
>I used Shailabh's per-tgid-disable patch to run my tests with per-tgid
>enabled and disabled. I used 'sa' command of 'acct' package to report
>results of 5 runs of 'mkthreads 1000 5000'.
>
>
>> Yes No Ovhd
>>user 0.14 0.15 -6%
>>system 1.61 1.54 +5%
>>elapsed 2.01 1.94 +3%
>>
>>Yes = tgid stats printed on exit
>>No = not printed
>>Ovhd = (Yes-No)/No * 100
>>
>>
>
>Here are test results:
>
> Yes No Ovhd
>user 1.77 0.44 302.27%
>system 0.06 0.06 0.00%
>

Please swap "user" label with "system" label. Sorry.

Also i forgot to attach the two files.

- jay

>elapsed 794.60 316.40 151.14%
>
>Also, the results of five runs of per-tgid-disabled were very
>consistent (3 runs of 0,44 seconds and 2 runs of 0.45), while
>those of per-tgid-enabled varies (1.56, 1.99, 1.54, 2.21, 1.57).
>
>The impact of per-tgid stats is too significant to ignore for
>those who do not need the per-tgid stats data.
>
>Another observation that i considered bad news is that all
>10 runs produced 1 to 5 recv() error with errno=105 (ENOBUF).
>
>Here I attach my csa_taskstats patch and my modified version of
>exit_recv.c.
>
>Regards,
> - jay
>
>
>
>>So even in this extreme case where the per-tgid stats are indeed
>>half of the total data, the overhead is not very significant.
>>
>>As pointed out earlier, more representative cases are
>>- single threaded apps (e.g. make -jX) where the current
>>taskstats interface already optimizes by not sending redundant per-tgid stats, or
>>- server-type multithreaded apps where the exits are going to be relatively infrequent (due to
>>reuse of thread pools) so the extra per-tgid output is not going to have much impact.
>>
>>I'd suggest we drop the idea of including this patch until we have data showing that
>>the overhead is an issue.
>>
>>--Shailabh
>>
>>
>>
>>#include <stdio.h>
>>#include <stdlib.h>
>>#include <sys/types.h>
>>#include <unistd.h>
>>#include <pthread.h>
>>
>>int n;
>>
>>void *slow_exit(void *arg)
>>{
>> int i = (int) arg;
>> usleep((n-i)*2);
>>}
>>
>>int main(int argc, char *argv[])
>>{
>> int i,rc, rep;
>> pthread_t *ppthread;
>>
>> n = 5 ;
>> if (argc > 1)
>> n = atoi(argv[1]);
>>
>> rep = 10;
>> if (argc > 2)
>> rep = atoi(argv[2]);
>>
>> ppthread = malloc(n * sizeof(pthread_t));
>> if (ppthread == NULL) {
>> printf("Memory allocation failure\n");
>> exit(-1);
>> }
>>
>> while (rep) {
>> for (i=0; i<n; i++) {
>> rc = pthread_create(&ppthread[i], NULL,
>> slow_exit, (void *)i);
>> if (rc) {
>> printf("Error creating thread %d\n", i);
>> exit(-1);
>> }
>> }
>> for (i=0; i<n; i++) {
>> rc = pthread_join(ppthread[i], NULL);
>> if (rc) {
>> printf("Error joining thread %d\n", i);
>> exit(-1);
>> }
>> }
>> rep--;
>> }
>>}
>>
>>
>>
>>
>>
>
>

[-- Attachment #2: csa_taskstats.patch --]
[-- Type: text/plain, Size: 10542 bytes --]

Index: linux/include/linux/taskstats.h
===================================================================
--- linux.orig/include/linux/taskstats.h 2006-06-19 18:27:38.881105605 -0700
+++ linux/include/linux/taskstats.h 2006-06-20 11:37:51.278901513 -0700
@@ -15,6 +15,11 @@
#ifndef _LINUX_TASKSTATS_H
#define _LINUX_TASKSTATS_H

+#ifdef __KERNEL__
+#include <linux/time.h>
+#include <linux/sched.h>
+#endif
+
/* Format for per-task data returned to userland when
* - a task exits
* - listener requests stats for a task
@@ -84,6 +89,40 @@ struct taskstats {

/* version of taskstats */
__u64 version;
+
+ /* Common Accounting Fields start */
+ __u32 ac_uid; /* User ID */
+ __u32 ac_gid; /* Group ID */
+ __u32 ac_pid; /* Process ID */
+ __u32 ac_ppid; /* Parent process ID */
+ struct timespec start_time; /* Start time */
+ struct timespec exit_time; /* Exit time */
+ __u64 ac_utime; /* User CPU time [usec] */
+ __u64 ac_stime; /* SYstem CPU time [usec] */
+ char ac_comm[TASK_COMM_LEN]; /* Command name */
+ /* Common Accounting Fields end */
+
+ /* CSA accounting fields start */
+ __u64 ac_sbu; /* System billing units */
+ __u16 csa_revision; /* CSA Revision */
+ __u8 csa_type; /* Record types */
+ __u8 csa_flag; /* Record flags */
+ __u8 ac_stat; /* Exit status */
+ __u8 ac_nice; /* Nice value */
+ __u8 ac_sched; /* Scheduling discipline */
+ __u8 pad0; /* Unused */
+ __u64 acct_rss_mem1; /* accumulated rss usage */
+ __u64 acct_vm_mem1; /* accumulated virtual memory usage */
+ __u64 hiwater_rss; /* High-watermark of RSS usage */
+ __u64 hiwater_vm; /* High-water virtual memory usage */
+ __u64 ac_minflt; /* Minor Page Fault */
+ __u64 ac_majflt; /* Major Page Fault */
+ __u64 ac_chr; /* bytes read */
+ __u64 ac_chw; /* bytes written */
+ __u64 ac_scr; /* read syscalls */
+ __u64 ac_scw; /* write syscalls */
+ __u64 ac_jid; /* Job ID */
+ /* CSA accounting fields end */

};

Index: linux/init/Kconfig
===================================================================
--- linux.orig/init/Kconfig 2006-06-19 18:27:38.913105990 -0700
+++ linux/init/Kconfig 2006-06-20 11:37:51.290901649 -0700
@@ -173,6 +173,31 @@ config TASK_DELAY_ACCT

Say N if unsure.

+config CSA_ACCT
+ bool "Enable CSA Job Accounting (EXPERIMENTAL)"
+ depends on TASKSTATS
+ help
+ Comprehensive System Accounting (CSA) provides job level
+ accounting of resource usage. The accounting records are
+ written by the kernel into a file. CSA user level scripts
+ and commands process the binary accounting records and
+ combine them by job identifier within system boot uptime
+ periods. These accounting records are then used to produce
+ reports and charge fees to users.
+
+ Say Y here if you want job level accounting to be compiled
+ into the kernel. Say M here if you want the writing of
+ accounting records portion of this feature to be a loadable
+ module. Say N here if you do not want job level accounting
+ (the default).
+
+ The CSA commands and scripts package needs to be installed
+ to process the CSA accounting records. See
+ http://oss.sgi.com/projects/csa for further information
+ about CSA and download instructions for the CSA commands
+ package and documentation.
+
+
config SYSCTL
bool "Sysctl support"
---help---
Index: linux/kernel/Makefile
===================================================================
--- linux.orig/kernel/Makefile 2006-06-19 18:27:38.929106183 -0700
+++ linux/kernel/Makefile 2006-06-20 11:37:51.290901649 -0700
@@ -40,6 +40,7 @@ obj-$(CONFIG_RCU_TORTURE_TEST) += rcutor
obj-$(CONFIG_RELAY) += relay.o
obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
obj-$(CONFIG_TASKSTATS) += taskstats.o
+obj-$(CONFIG_CSA_ACCT) += csa.o

ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
Index: linux/kernel/csa.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux/kernel/csa.c 2006-06-20 11:37:51.294901694 -0700
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2006 Silicon Graphics, Inc All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * Contact information: Silicon Graphics, Inc., 1500 Crittenden Lane,
+ * Mountain View, CA 94043, or:
+ *
+ * http://www.sgi.com
+ */
+
+#include <linux/taskstats.h>
+#include <linux/csa_kern.h>
+
+int csa_add_tsk(struct taskstats *stats, struct task_struct *p)
+{
+ stats->version = 0x3132333435363738;
+ stats->ac_uid = 0x39393939; /* p->uid; */
+ stats->ac_gid = 0x38383838; /* p->gid; */
+ stats->ac_pid = p->pid;
+ stats->ac_ppid = (p->parent) ? p->parent->pid : 0;
+ stats->ac_utime = p->utime * USEC_PER_TICK;
+ stats->ac_stime = p->stime * USEC_PER_TICK;
+ /* Each process gets a minimum of a half tick cpu time */
+ if ((stats->ac_utime == 0) && (stats->ac_stime == 0)) {
+ stats->ac_stime = USEC_PER_TICK/2;
+ }
+
+ stats->start_time = p->start_time;
+ do_posix_clock_monotonic_gettime(&stats->exit_time);
+ strncpy(stats->ac_comm, p->comm, sizeof(stats->ac_comm));
+
+ stats->ac_sbu = 0;
+ stats->csa_revision = REV_CSA;
+ stats->csa_type = 0;
+ stats->csa_flag = 0;
+ stats->ac_stat = p->exit_code;
+ stats->ac_nice = task_nice(p);
+ stats->ac_sched = p->policy;
+ stats->acct_rss_mem1 = p->acct_rss_mem1;
+ stats->acct_vm_mem1 = p->acct_vm_mem1;
+ if (p->mm) {
+ stats->hiwater_rss = p->mm->hiwater_rss;
+ stats->hiwater_vm = p->mm->hiwater_vm;
+ }
+ stats->ac_minflt = p->min_flt;
+ stats->ac_majflt = p->maj_flt;
+ stats->ac_chr = p->rchar;
+ stats->ac_chw = p->wchar;
+ stats->ac_scr = p->syscr;
+ stats->ac_scw = p->syscw;
+ stats->ac_jid = 0xffffffffffffffff;
+ return 0;
+}
Index: linux/kernel/taskstats.c
===================================================================
--- linux.orig/kernel/taskstats.c 2006-06-20 11:34:51.652867983 -0700
+++ linux/kernel/taskstats.c 2006-06-20 11:37:51.298901739 -0700
@@ -19,6 +19,7 @@
#include <linux/kernel.h>
#include <linux/taskstats_kern.h>
#include <linux/delayacct.h>
+#include <linux/csa_kern.h>
#include <net/genetlink.h>
#include <asm/atomic.h>

@@ -123,8 +124,16 @@ static int fill_pid(pid_t pid, struct ta
*/

rc = delayacct_add_tsk(stats, tsk);
+/*
+ if (rc)
+ goto err;
+ */
+ rc = csa_add_tsk(stats, tsk);
+ if (rc) {
+ goto err;
+ }

- /* Define err: label here if needed */
+err: /* Define err: label here if needed */
put_task_struct(tsk);
return rc;

@@ -269,12 +278,14 @@ void taskstats_exit_send(struct task_str
size = 2 * size; /* PID + STATS + TGID + STATS */

rc = prepare_reply(NULL, TASKSTATS_CMD_NEW, &rep_skb, &reply, size);
- if (rc < 0)
+ if (rc < 0) {
goto ret;
+ }

rc = fill_pid(tsk->pid, tsk, tidstats);
- if (rc < 0)
+ if (rc < 0) {
goto err_skb;
+ }

tidstats->version = TASKSTATS_VERSION;

Index: linux/include/linux/csa_kern.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux/include/linux/csa_kern.h 2006-06-20 11:37:51.314901921 -0700
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2006 Silicon Graphics, Inc All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
+ * Mountain View, CA 94043, or:
+ *
+ * http://www.sgi.com
+ */
+/*
+ * CSA (Comprehensive System Accounting)
+ * Job Accounting for Linux
+ *
+ * This header file contains the definitions needed for job
+ * accounting. The kernel CSA accounting module code and all
+ * user-level programs that try to write or process the binary job
+ * accounting data must include this file.
+ *
+ * This kernel header file and the csa.h in the csa userland source
+ * rpm share same data struct declaration and #define's. Do not modify
+ * one without modify the other one as well. The compatibility between
+ * userland and the kernel is ensured by using the 'ah_revision' field
+ * of struct achead.
+ *
+ */
+
+#ifndef _CSA_KERN_H
+#define _CSA_KERN_H
+
+#include <linux/time.h>
+
+extern int csa_add_tsk(struct taskstats *, struct task_struct *);
+
+/*
+ * Record revision levels.
+ *
+ * These are incremented to indicate that a record's format has changed since
+ * a previous release.
+ *
+ * History: 05000 The first rev in Linux
+ * 06000 Major rework to clean up unused fields and features.
+ * No binary compatibility with earlier rev.
+ * 07000 Convert to taskstats interface
+ *
+ * NOTE: The header revision number was defined as 02400 in earlier version.
+ * However, since ah_revision was defined as 15-bit field (ah_magic
+ * takes up 17 bits), the revision number is read as twice the value in
+ * new code. So, define it to be 05000 accordingly.
+ */
+#define REV_CSA 07000 /* Kernel: CSA base record */
+
+
+/* this defines can be removed once they're available in kernel header files */
+/* #define USEC_PER_SEC 1000000L */ /* number of usecs for 1 second */
+#define USEC_PER_TICK (USEC_PER_SEC/HZ)
+
+
+#endif /* _CSA_KERN_H */

[-- Attachment #3: exit_recv.c --]
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/* getdelays.c
*
* Utility to get per-pid and per-tgid delay accounting statistics
* Also illustrates usage of the taskstats interface
*
* Copyright (C) Shailabh Nagar, IBM Corp. 2005
* Copyright (C) Balbir Singh, IBM Corp. 2006
* Copyright (c) Jay Lan, SGI. 2006
*
*/

#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/types.h>
#include <signal.h>

#include <linux/genetlink.h>
#include <taskstats.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 { printf(fmt, ##arg); exit(code); } while (0)
int done = 0;

int dbg=0, Delayacct=0;
__u64 stime, utime;
#define PRINTF(fmt, arg...) { \
if (dbg) { \
printf(fmt, ##arg); \
} \
}
/*
* Create a raw netlink socket and bind
*/
static int create_nl_socket(int protocol, int groups)
{
socklen_t addr_len;
int fd;
struct sockaddr_nl local;

fd = socket(AF_NETLINK, SOCK_RAW, protocol);
if (fd < 0)
return -1;

memset(&local, 0, sizeof(local));
local.nl_family = AF_NETLINK;
local.nl_groups = groups;

if (bind(fd, (struct sockaddr *) &local, sizeof(local)) < 0)
goto error;

return fd;
error:
close(fd);
return -1;
}

int sendto_fd(int s, const char *buf, int bufLen)
{
struct sockaddr_nl nladdr;
int r;

memset(&nladdr, 0, sizeof(nladdr));
nladdr.nl_family = AF_NETLINK;

while ((r = sendto(s, 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
*/
int get_family_id(int sd)
{
struct {
struct nlmsghdr n;
struct genlmsghdr g;
char buf[256];
} family_req;
struct {
struct nlmsghdr n;
struct genlmsghdr g;
char buf[256];
} ans;

int id;
struct nlattr *na;
int rep_len;

/* Get family name */
family_req.n.nlmsg_type = GENL_ID_CTRL;
family_req.n.nlmsg_flags = NLM_F_REQUEST;
family_req.n.nlmsg_seq = 0;
family_req.n.nlmsg_pid = getpid();
family_req.n.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
family_req.g.cmd = CTRL_CMD_GETFAMILY;
family_req.g.version = 0x1;
na = (struct nlattr *) GENLMSG_DATA(&family_req);
na->nla_type = CTRL_ATTR_FAMILY_NAME;
na->nla_len = strlen(TASKSTATS_GENL_NAME) + 1 + NLA_HDRLEN;
strcpy(NLA_DATA(na), TASKSTATS_GENL_NAME);
family_req.n.nlmsg_len += NLMSG_ALIGN(na->nla_len);

if (sendto_fd(sd, (char *) &family_req, family_req.n.nlmsg_len) < 0)
err(1, "error sending message via Netlink\n");

rep_len = recv(sd, &ans, sizeof(ans), 0);

if (rep_len < 0)
err(1, "error receiving reply message via Netlink\n");

/* Validate response message */
if (!NLMSG_OK((&ans.n), rep_len))
err(1, "invalid reply message received via Netlink\n");

if (ans.n.nlmsg_type == NLMSG_ERROR) { /* error */
printf("error received NACK - leaving\n");
exit(1);
}

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;
}

void print_taskstats(struct taskstats *t)
{
printf("\n\nCPU %15s%15s%15s%15s\n"
" %15llu%15llu%15llu%15llu\n"
"IO %15s%15s\n"
" %15llu%15llu\n"
"MEM %15s%15s\n"
" %15llu%15llu\n\n",
"count", "real total", "virtual total", "delay total",
t->cpu_count, t->cpu_run_real_total, t->cpu_run_virtual_total,
t->cpu_delay_total,
"count", "delay total",
t->blkio_count, t->blkio_delay_total,
"count", "delay total", t->swapin_count, t->swapin_delay_total);
}

void print_csa(struct taskstats *t)
{
int sec, nsec;
sec = t->exit_time.tv_sec - t->start_time.tv_sec;
nsec = t->exit_time.tv_nsec - t->start_time.tv_nsec;
printf("Command='%s'\n stime=%15llu, utime=%15llu, elapsed=%15llu msec\n",
t->ac_comm, t->ac_stime, t->ac_utime, sec*1000 + nsec/1000000);
stime += t->ac_stime;
utime += t->ac_utime;
}

void sigchld(int sig)
{
done = 1;
}

int main(int argc, char *argv[])
{
int rc;
int sk_nl;
struct nlmsghdr *nlh;
struct genlmsghdr *genlhdr;
__u16 id;
struct nlattr *na;
struct {
struct nlmsghdr n;
struct genlmsghdr g;
char buf[800];
} exitmsg;
int fd;

/* For receiving */
struct sockaddr_nl kern_nla, from_nla;
socklen_t from_nla_len;
int recv_len;

int nl_sd = -1;
int rep_len;
int len = 0;
int aggr_len, len2;
struct sockaddr_nl nladdr;
pid_t tid = 0;
pid_t rtid = 0;
int c;
int count = 0, csa_summary=0;
int write_file = 1;
struct sigaction act = {
.sa_handler = SIG_IGN,
};
struct sigaction tact = {
.sa_handler = sigchld,
};

if (sigaction(SIGCHLD, &tact, NULL) < 0)
err(1, "sigaction failed for SIGCHLD\n");

while (1) {
c = getopt(argc, argv, "cdDw");
if (c < 0)
break;

switch (c) {
case 'c':
printf("display csa\n");
csa_summary = 1;
break;

case 'd':
printf("exit_recv: debug on\n");
dbg = 1;
break;

case 'D':
printf("Delayacct summary ON\n");
Delayacct = 1;
break;

case 'w': /* DON'T write data to a file */
printf("exit_recv: write_file OFF\n");
write_file = 0;
break;

default: {
printf("Unknown option %d\n", c);
exit(-1);
}
}
}

if (write_file)
if ((fd = open("/var/csa/acct", O_WRONLY | O_CREAT | O_TRUNC,
S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) == -1) {
perror("Cannot open output file\n"); exit(1);
}

/* Open a NETLINK_GENERIC socket with TASKSTATS_LISTEN_GROUP */

if ((nl_sd =
create_nl_socket(NETLINK_GENERIC, TASKSTATS_LISTEN_GROUP)) < 0)
err(1, "error creating Netlink socket\n");

if (sigaction(SIGINT, &act, NULL) < 0)
err(1, "sigaction failed for SIGINT\n");

do {
int i;

rep_len = recv(nl_sd, &exitmsg, sizeof(exitmsg), 0);
PRINTF("\n\treceived %d bytes\n", rep_len);
nladdr.nl_family = AF_NETLINK;
nladdr.nl_groups = TASKSTATS_LISTEN_GROUP;

if (exitmsg.n.nlmsg_type == NLMSG_ERROR) { /* error */
printf("error received NACK - leaving\n");
exit(1);
}

if (rep_len < 0) {
printf("error receiving reply message via Netlink, rep_len=%d, errno=%d\n",
rep_len, errno);
continue;
}

PRINTF("nlmsghdr size=%d, nlmsg_len=%d, rep_len=%d\n",
sizeof(struct nlmsghdr), exitmsg.n.nlmsg_len, rep_len);
/* Validate response message */
if (!NLMSG_OK((&exitmsg.n), rep_len))
err(1, "invalid reply message received via Netlink\n");
/* #define NLMSG_OK(nlh,len) ((len) >= (int)sizeof(struct nlmsghdr) && \
(nlh)->nlmsg_len >= sizeof(struct nlmsghdr) && \
(nlh)->nlmsg_len <= (len))
*/

rep_len = GENLMSG_PAYLOAD(&exitmsg.n);

na = (struct nlattr *) GENLMSG_DATA(&exitmsg);
len = 0;
i = 0;
while (len < rep_len) {
len += NLA_ALIGN(na->nla_len);
switch (na->nla_type) {
case TASKSTATS_TYPE_AGGR_PID:
/* Fall through */
case TASKSTATS_TYPE_AGGR_TGID:
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 (Delayacct)
print_taskstats((struct taskstats *) NLA_DATA(na));
if (fd > 0) {
if (write(fd, NLA_DATA(na), na->nla_len) < 0) {
err(1,"write error\n");
}
}
if (csa_summary)
print_csa((struct taskstats *)NLA_DATA(na));
break;
default:
printf("Unknown nested nla_type %d\n", na->nla_type);
break;
}
len2 += NLA_ALIGN(na->nla_len);
na = (struct nlattr *) ((char *) na + len2);
if (done)
break;
}
break;

default:
printf("Unknown nla_type %d\n", na->nla_type);
break;
}
na = (struct nlattr *) (GENLMSG_DATA(&exitmsg) + len);
if (done)
break;
}
if (done)
break;
}
while (1);

printf("Total taskstats STATS read %d, stime=%llu, utime=%llu\n",
count, stime, utime);
close(nl_sd);
if (fd > 0)
close(fd);
return 0;
}