From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kay Sievers Date: Sun, 26 Dec 2004 03:13:27 +0000 Subject: udevd - throttle fork() if we get to many childs in running Message-Id: <1104030808.5805.34.camel@localhost.localdomain> MIME-Version: 1 Content-Type: multipart/mixed; boundary="=-4ZjmiYq6uDYJhRf41otX" List-Id: To: linux-hotplug@vger.kernel.org --=-4ZjmiYq6uDYJhRf41otX Content-Type: text/plain Content-Transfer-Encoding: 7bit We count the number of "R" processes in our session group and stop forking if we reach a specified limit. Sleeping events are not counted. Running hotplug.d/ and dev.d/ scripts are counted, as they belong to our session group. This should help the "lots of disks" setups where the kernel may spit out lots of events in parallel. Thanks, Kay --=-4ZjmiYq6uDYJhRf41otX Content-Disposition: inline; filename=udevd-throttle-fork-01.patch Content-Type: text/x-patch; name=udevd-throttle-fork-01.patch; charset=UTF-8 Content-Transfer-Encoding: 7bit diff -Nru a/udevd.c b/udevd.c --- a/udevd.c 2004-12-26 03:53:53 +01:00 +++ b/udevd.c 2004-12-26 03:53:53 +01:00 @@ -28,11 +28,13 @@ #include #include #include +#include +#include +#include #include #include #include #include -#include #include #include @@ -45,6 +47,7 @@ /* global variables*/ static int udevsendsock; +static int sid; static int pipefds[2]; static long startup_time; @@ -133,6 +136,8 @@ /* child */ close(udevsendsock); logging_close(); + + setpriority(PRIO_PROCESS, 0, UDEV_PRIORITY); execve(udev_bin, argv, msg->envp); dbg("exec of child failed"); _exit(1); @@ -140,9 +145,6 @@ case -1: dbg("fork of child failed"); run_queue_delete(msg); - /* note: we never managed to run, so we had no impact on - * running_with_devpath(), so don't bother setting run_exec_q - */ break; default: /* get SIGCHLD in main loop */ @@ -151,6 +153,60 @@ } } +static int running_processes_in_session(void) +{ + DIR *dir; + struct dirent *dent; + int running = 0; + + dir = opendir("/proc"); + if (!dir) + return -1; + + /* read all processes in /proc */ + for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) { + int f; + char procdir[64]; + char line[256]; + const char *pos; + pid_t pid, ppid, pgrp, session; + char state; + + if (!isdigit(dent->d_name[0])) + continue; + + snprintf(procdir, sizeof(procdir), "/proc/%s/stat", dent->d_name); + procdir[sizeof(procdir)-1] = '\0'; + + f = open(procdir, O_RDONLY); + if (f == -1) + continue; + + read(f, line, sizeof(line)); + close(f); + + /* skip ugly program name */ + pos = strrchr(line, ')') + 2; + + pid = strtol(line, NULL, 10); + if (sscanf(pos, "%c %d %d %d ", &state, &ppid, &pgrp, &session) != 4) + continue; + + /* count only processes in our session */ + if (session != sid) + continue; + + /* count only running, no sleeping processes */ + if (state != 'R') + continue; + + running++; + } + closedir(dir); + + return running; +} + static int compare_devpath(const char *running, const char *waiting) { int i; @@ -207,13 +263,26 @@ struct hotplug_msg *loop_msg; struct hotplug_msg *tmp_msg; struct hotplug_msg *msg; + int active; + int recheck = THROTTLE_RUNNING_CHILDS_COUNT; list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) { + /* check running processes in our session and possibly throttle */ + if (recheck >= THROTTLE_RUNNING_CHILDS_COUNT) { + active = running_processes_in_session(); + if (active > THROTTLE_RUNNING_CHILDS_COUNT) { + dbg("skip exec, %d processes already in running state", active); + return; + } + recheck = 0; + } + msg = running_with_devpath(loop_msg); if (!msg) { /* move event to run list */ list_move_tail(&loop_msg->list, &running_list); udev_run(loop_msg); + recheck++; dbg("moved seq %llu to running list", loop_msg->seqnum); } else { dbg("delay seq %llu (%s), cause seq %llu (%s) is still running", @@ -490,7 +559,10 @@ close(fd); /* become session leader */ - setsid(); + sid = setsid(); + + /*set a reasonable scheduling priority for the daemon */ + setpriority(PRIO_PROCESS, 0, UDEVD_PRIORITY); /* setup signal handler pipe */ retval = pipe(pipefds); diff -Nru a/udevd.h b/udevd.h --- a/udevd.h 2004-12-26 03:53:53 +01:00 +++ b/udevd.h 2004-12-26 03:53:53 +01:00 @@ -28,9 +28,19 @@ #define UDEVD_SOCK_PATH "udevd" #define SEND_WAIT_MAX_SECONDS 3 #define SEND_WAIT_LOOP_PER_SECOND 10 + +#define UDEVD_PRIORITY -5 +#define UDEV_PRIORITY -2 + +/* duration of initialization phase with shorter timeout */ #define INIT_TIME_SEC 5 #define EVENT_INIT_TIMEOUT_SEC 2 + +/* timeout to wait for missing events */ #define EVENT_TIMEOUT_SEC 10 + +/* start to throttle forking if maximum number of running childs in our session is reached */ +#define THROTTLE_RUNNING_CHILDS_COUNT 10 /* environment buffer, should match the kernel's size in lib/kobject_uevent.h */ #define HOTPLUG_BUFFER_SIZE 1024 --=-4ZjmiYq6uDYJhRf41otX-- ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://productguide.itmanagersjournal.com/ _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel