diff options
| -rw-r--r-- | Documentation/accounting/delay-accounting.txt | 115 | ||||
| -rw-r--r-- | Documentation/accounting/getdelays.c | 376 | ||||
| -rw-r--r-- | Documentation/accounting/taskstats.txt | 2 |
3 files changed, 493 insertions, 0 deletions
diff --git a/Documentation/accounting/delay-accounting.txt b/Documentation/accounting/delay-accounting.txt new file mode 100644 index 0000000..f3dc0ca --- /dev/null +++ b/Documentation/accounting/delay-accounting.txt @@ -0,0 +1,115 @@ +Delay accounting +---------------- + +Tasks encounter delays in execution when they wait +for some kernel resource to become available e.g. a +runnable task may wait for a free CPU to run on. + +The per-task delay accounting functionality measures +the delays experienced by a task while + +a) waiting for a CPU (while being runnable) +b) completion of synchronous block I/O initiated by the task +c) swapping in pages + +and makes these statistics available to userspace through +the taskstats interface. + +Such delays provide feedback for setting a task's cpu priority, +io priority and rss limit values appropriately. Long delays for +important tasks could be a trigger for raising its corresponding priority. + +The functionality, through its use of the taskstats interface, also provides +delay statistics aggregated for all tasks (or threads) belonging to a +thread group (corresponding to a traditional Unix process). This is a commonly +needed aggregation that is more efficiently done by the kernel. + +Userspace utilities, particularly resource management applications, can also +aggregate delay statistics into arbitrary groups. To enable this, delay +statistics of a task are available both during its lifetime as well as on its +exit, ensuring continuous and complete monitoring can be done. + + +Interface +--------- + +Delay accounting uses the taskstats interface which is described +in detail in a separate document in this directory. Taskstats returns a +generic data structure to userspace corresponding to per-pid and per-tgid +statistics. The delay accounting functionality populates specific fields of +this structure. See + include/linux/taskstats.h +for a description of the fields pertaining to delay accounting. +It will generally be in the form of counters returning the cumulative +delay seen for cpu, sync block I/O, swapin etc. + +Taking the difference of two successive readings of a given +counter (say cpu_delay_total) for a task will give the delay +experienced by the task waiting for the corresponding resource +in that interval. + +When a task exits, records containing the per-task and per-process statistics +are sent to userspace without requiring a command. More details are given in +the taskstats interface description. + +The getdelays.c userspace utility in this directory allows simple commands to +be run and the corresponding delay statistics to be displayed. It also serves +as an example of using the taskstats interface. + +Usage +----- + +Compile the kernel with + CONFIG_TASK_DELAY_ACCT=y + CONFIG_TASKSTATS=y + +Enable the accounting at boot time by adding +the following to the kernel boot options + delayacct + +and after the system has booted up, use a utility +similar to getdelays.c to access the delays +seen by a given task or a task group (tgid). +The utility also allows a given command to be +executed and the corresponding delays to be +seen. + +General format of the getdelays command + +getdelays [-t tgid] [-p pid] [-c cmd...] + + +Get delays, since system boot, for pid 10 +# ./getdelays -p 10 +(output similar to next case) + +Get sum of delays, since system boot, for all pids with tgid 5 +# ./getdelays -t 5 + + +CPU count real total virtual total delay total + 7876 92005750 100000000 24001500 +IO count delay total + 0 0 +MEM count delay total + 0 0 + +Get delays seen in executing a given simple command +# ./getdelays -c ls / + +bin data1 data3 data5 dev home media opt root srv sys usr +boot data2 data4 data6 etc lib mnt proc sbin subdomain tmp var + + +CPU count real total virtual total delay total + 6 4000250 4000000 0 +IO count delay total + 0 0 +MEM count delay total + 0 0 + + + + + + diff --git a/Documentation/accounting/getdelays.c b/Documentation/accounting/getdelays.c new file mode 100644 index 0000000..33de89e --- /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; +} diff --git a/Documentation/accounting/taskstats.txt b/Documentation/accounting/taskstats.txt index ad9b699..acc6b4f 100644 --- a/Documentation/accounting/taskstats.txt +++ b/Documentation/accounting/taskstats.txt @@ -39,6 +39,8 @@ belongs (the task does not need to be the thread group leader). The need for per-tgid stats to be sent for each exiting task is explained in the per-tgid stats section below. +getdelays.c is a simple utility demonstrating usage of the taskstats interface +for reporting delay accounting statistics. Interface --------- |