cgroups: move cgroup_event_listener.c to tools/cgroup
Move the cgroup_event_listener.c tool from Documentation into the new tools/cgroup directory. This change involves wiring cgroup_event_listener.c into the tools/ make system so that is can be built with: $ make tools/cgroup Signed-off-by: Greg Thelen <gthelen@google.com> Signed-off-by: Tejun Heo <tj@kernel.org>
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@@ -4,8 +4,6 @@ blkio-controller.txt
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- Description for Block IO Controller, implementation and usage details.
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cgroups.txt
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- Control Groups definition, implementation details, examples and API.
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cgroup_event_listener.c
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- A user program for cgroup listener.
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cpuacct.txt
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- CPU Accounting Controller; account CPU usage for groups of tasks.
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cpusets.txt
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@@ -1,110 +0,0 @@
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/*
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* cgroup_event_listener.c - Simple listener of cgroup events
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*
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* Copyright (C) Kirill A. Shutemov <kirill@shutemov.name>
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*/
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#include <assert.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <libgen.h>
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#include <limits.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/eventfd.h>
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#define USAGE_STR "Usage: cgroup_event_listener <path-to-control-file> <args>\n"
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int main(int argc, char **argv)
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{
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int efd = -1;
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int cfd = -1;
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int event_control = -1;
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char event_control_path[PATH_MAX];
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char line[LINE_MAX];
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int ret;
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if (argc != 3) {
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fputs(USAGE_STR, stderr);
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return 1;
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}
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cfd = open(argv[1], O_RDONLY);
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if (cfd == -1) {
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fprintf(stderr, "Cannot open %s: %s\n", argv[1],
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strerror(errno));
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goto out;
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}
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ret = snprintf(event_control_path, PATH_MAX, "%s/cgroup.event_control",
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dirname(argv[1]));
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if (ret >= PATH_MAX) {
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fputs("Path to cgroup.event_control is too long\n", stderr);
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goto out;
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}
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event_control = open(event_control_path, O_WRONLY);
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if (event_control == -1) {
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fprintf(stderr, "Cannot open %s: %s\n", event_control_path,
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strerror(errno));
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goto out;
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}
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efd = eventfd(0, 0);
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if (efd == -1) {
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perror("eventfd() failed");
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goto out;
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}
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ret = snprintf(line, LINE_MAX, "%d %d %s", efd, cfd, argv[2]);
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if (ret >= LINE_MAX) {
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fputs("Arguments string is too long\n", stderr);
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goto out;
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}
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ret = write(event_control, line, strlen(line) + 1);
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if (ret == -1) {
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perror("Cannot write to cgroup.event_control");
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goto out;
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}
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while (1) {
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uint64_t result;
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ret = read(efd, &result, sizeof(result));
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if (ret == -1) {
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if (errno == EINTR)
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continue;
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perror("Cannot read from eventfd");
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break;
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}
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assert(ret == sizeof(result));
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ret = access(event_control_path, W_OK);
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if ((ret == -1) && (errno == ENOENT)) {
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puts("The cgroup seems to have removed.");
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ret = 0;
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break;
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}
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if (ret == -1) {
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perror("cgroup.event_control "
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"is not accessible any more");
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break;
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}
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printf("%s %s: crossed\n", argv[1], argv[2]);
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}
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out:
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if (efd >= 0)
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close(efd);
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if (event_control >= 0)
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close(event_control);
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if (cfd >= 0)
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close(cfd);
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return (ret != 0);
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}
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@@ -399,8 +399,7 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
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9.10 Memory thresholds
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Memory controller implements memory thresholds using cgroups notification
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API. You can use Documentation/cgroups/cgroup_event_listener.c to test
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it.
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API. You can use tools/cgroup/cgroup_event_listener.c to test it.
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(Shell-A) Create cgroup and run event listener
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# mkdir /cgroup/A
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