[PATCH] per-task-delay-accounting: documentation

Some documentation for delay accounting.

Signed-off-by: Shailabh Nagar <nagar@watson.ibm.com>
Signed-off-by: Balbir Singh <balbir@in.ibm.com>
Cc: Jes Sorensen <jes@sgi.com>
Cc: Peter Chubb <peterc@gelato.unsw.edu.au>
Cc: Erich Focht <efocht@ess.nec.de>
Cc: Levent Serinol <lserinol@gmail.com>
Cc: Jay Lan <jlan@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 376 insertions, 0 deletions

diff --git a/Documentation/accounting/getdelays.c b/Documentation/accounting/getdelays.c
new file mode 100644
index 000000000000..33de89e56a3d
--- /dev/null
+++ b/Documentation/accounting/getdelays.c
@@ -0,0 +1,376 @@
+/* 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
+ *
+ */
+
+#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 <linux/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;
+
+/*
+ * 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 sigchld(int sig)
+{
+    done = 1;
+}
+
+int main(int argc, char *argv[])
+{
+    int rc;
+    int sk_nl;
+    struct nlmsghdr *nlh;
+    struct genlmsghdr *genlhdr;
+    char *buf;
+    struct taskstats_cmd_param *param;
+    __u16 id;
+    struct nlattr *na;
+
+    /* For receiving */
+    struct sockaddr_nl kern_nla, from_nla;
+    socklen_t from_nla_len;
+    int recv_len;
+    struct taskstats_reply *reply;
+
+    struct {
+        struct nlmsghdr n;
+        struct genlmsghdr g;
+        char buf[256];
+    } req;
+
+    struct {
+        struct nlmsghdr n;
+        struct genlmsghdr g;
+        char buf[256];
+    } ans;
+
+    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 cmd_type = TASKSTATS_TYPE_TGID;
+    int c, status;
+    int forking = 0;
+    struct sigaction act = {
+        .sa_handler = SIG_IGN,
+        .sa_mask = SA_NOMASK,
+    };
+    struct sigaction tact ;
+
+    if (argc < 3) {
+        printf("usage %s [-t tgid][-p pid][-c cmd]\n", argv[0]);
+        exit(-1);
+    }
+
+    tact.sa_handler = sigchld;
+    sigemptyset(&tact.sa_mask);
+    if (sigaction(SIGCHLD, &tact, NULL) < 0)
+        err(1, "sigaction failed for SIGCHLD\n");
+
+    while (1) {
+
+        c = getopt(argc, argv, "t:p:c:");
+        if (c < 0)
+            break;
+
+        switch (c) {
+        case 't':
+            tid = atoi(optarg);
+            if (!tid)
+                err(1, "Invalid tgid\n");
+            cmd_type = TASKSTATS_CMD_ATTR_TGID;
+            break;
+        case 'p':
+            tid = atoi(optarg);
+            if (!tid)
+                err(1, "Invalid pid\n");
+            cmd_type = TASKSTATS_CMD_ATTR_TGID;
+            break;
+        case 'c':
+            opterr = 0;
+            tid = fork();
+            if (tid < 0)
+                err(1, "fork failed\n");
+
+            if (tid == 0) {     /* child process */
+                if (execvp(argv[optind - 1], &argv[optind - 1]) < 0) {
+                    exit(-1);
+                }
+            }
+            forking = 1;
+            break;
+        default:
+            printf("usage %s [-t tgid][-p pid][-c cmd]\n", argv[0]);
+            exit(-1);
+            break;
+        }
+        if (c == 'c')
+            break;
+    }
+
+    /* Construct Netlink request message */
+
+    /* Send Netlink request message & get reply */
+
+    if ((nl_sd =
+         create_nl_socket(NETLINK_GENERIC, TASKSTATS_LISTEN_GROUP)) < 0)
+        err(1, "error creating Netlink socket\n");
+
+
+    id = get_family_id(nl_sd);
+
+    /* Send command needed */
+    req.n.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
+    req.n.nlmsg_type = id;
+    req.n.nlmsg_flags = NLM_F_REQUEST;
+    req.n.nlmsg_seq = 0;
+    req.n.nlmsg_pid = tid;
+    req.g.cmd = TASKSTATS_CMD_GET;
+    na = (struct nlattr *) GENLMSG_DATA(&req);
+    na->nla_type = cmd_type;
+    na->nla_len = sizeof(unsigned int) + NLA_HDRLEN;
+    *(__u32 *) NLA_DATA(na) = tid;
+    req.n.nlmsg_len += NLMSG_ALIGN(na->nla_len);
+
+
+    if (!forking && sendto_fd(nl_sd, (char *) &req, req.n.nlmsg_len) < 0)
+        err(1, "error sending message via Netlink\n");
+
+    act.sa_handler = SIG_IGN;
+    sigemptyset(&act.sa_mask);
+    if (sigaction(SIGINT, &act, NULL) < 0)
+        err(1, "sigaction failed for SIGINT\n");
+
+    do {
+        int i;
+        struct pollfd pfd;
+        int pollres;
+
+        pfd.events = 0xffff & ~POLLOUT;
+        pfd.fd = nl_sd;
+        pollres = poll(&pfd, 1, 5000);
+        if (pollres < 0 || done) {
+            break;
+        }
+
+        rep_len = recv(nl_sd, &ans, sizeof(ans), 0);
+        nladdr.nl_family = AF_NETLINK;
+        nladdr.nl_groups = TASKSTATS_LISTEN_GROUP;
+
+        if (ans.n.nlmsg_type == NLMSG_ERROR) {  /* error */
+            printf("error received NACK - leaving\n");
+            exit(1);
+        }
+
+        if (rep_len < 0) {
+            err(1, "error receiving reply message via Netlink\n");
+            break;
+        }
+
+        /* Validate response message */
+        if (!NLMSG_OK((&ans.n), rep_len))
+            err(1, "invalid reply message received via Netlink\n");
+
+        rep_len = GENLMSG_PAYLOAD(&ans.n);
+
+        na = (struct nlattr *) GENLMSG_DATA(&ans);
+        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);
+                        break;
+                    case TASKSTATS_TYPE_TGID:
+                        rtid = *(int *) NLA_DATA(na);
+                        break;
+                    case TASKSTATS_TYPE_STATS:
+                        if (rtid == tid) {
+                            print_taskstats((struct taskstats *)
+                                            NLA_DATA(na));
+                            done = 1;
+                        }
+                        break;
+                    }
+                    len2 += NLA_ALIGN(na->nla_len);
+                    na = (struct nlattr *) ((char *) na + len2);
+                    if (done)
+                        break;
+                }
+            }
+            na = (struct nlattr *) (GENLMSG_DATA(&ans) + len);
+            if (done)
+                break;
+        }
+        if (done)
+            break;
+    }
+    while (1);
+
+    close(nl_sd);
+    return 0;
+}