/etc/compctl-unlimited control file support

Compctl client now works as simple server-less agent if
/etc/compctl-unlimited exists; so-called 'kamenolom mode'.

README.client

@@ -45,3 +45,11 @@ Examples
 
     compctl --limitmem 4096
     compctl --kill 27134
+
+
+Files
+=====
+
+If /etc/compctl-unlimited exists, compctl acts as a simple serverless agent
+that allows launching computations (with priority reduced as usual), but
+not limiting their memory usage or killing them.

compctl.1

@@ -58,5 +58,9 @@ compctl --limitmem 4096
 .br
 compctl --kill 27134
 .br
+.SH FILES
+If \fB/etc/compctl-unlimited\fP exists, compctl acts as a simple
+serverless agent that allows launching computations (with priority
+reduced as usual), but not limiting their memory usage or killing them.
 .SH AUTHOR
 \fBcompctl\fP was written by Petr Baudis <pasky@ucw.cz>.

compctl.c

@@ -13,6 +13,9 @@
 #include "common.h"
 
 
+bool unlimited;
+
+
 char *
 daemon_chat(char *cmd)
 {
@@ -99,12 +102,14 @@ help(FILE *f)
 int
 run(int argc, char *argv[])
 {
+	if (!unlimited) {
 		char *line = daemon_chat("blessme");
 		if (line[0] != '1') {
 			fprintf(stderr, "%s\n", *line ? line : "unexpected hangup");
 			return EXIT_FAILURE;
 		}
 		free(line);
+	}
 
 	setpgrp();
 	if (setpriority(PRIO_PROCESS, 0, COMPNICE) < 0)
@@ -133,6 +138,11 @@ screen(int argc, char *argv[])
 void
 kill_task(pid_t pid)
 {
+	if (unlimited) {
+		fputs("Killing computations not possible when computations are not limited..\n", stderr);
+		exit(EXIT_FAILURE);
+	}
+
 	char cmd[256]; snprintf(cmd, sizeof(cmd), "kill %d", pid);
 	char *line = daemon_chat(cmd);
 	if (line[0] != '1') {
@@ -145,6 +155,11 @@ kill_task(pid_t pid)
 void
 kill_all(void)
 {
+	if (unlimited) {
+		fputs("Killing computations not possible when computations are not limited..\n", stderr);
+		exit(EXIT_FAILURE);
+	}
+
 	char *line = daemon_chat("killall");
 	if (line[0] != '1') {
 		fprintf(stderr, "%s\n", *line ? line : "unexpected hangup");
@@ -157,6 +172,11 @@ kill_all(void)
 void
 limit_mem(size_t limit)
 {
+	if (unlimited) {
+		fputs("Computations are not limited.\n", stderr);
+		exit(EXIT_FAILURE);
+	}
+
 	char cmd[256];
 	snprintf(cmd, sizeof(cmd), "limitmem %zu", limit * 1048576);
 	char *line = daemon_chat(cmd);
@@ -175,6 +195,11 @@ limit_mem(size_t limit)
 void
 usage(void)
 {
+	if (unlimited) {
+		puts("unlimited");
+		return;
+	}
+
 	size_t usage = cgroup_get_mem_usage(chier, cgroup);
 	size_t limit = cgroup_get_mem_limit(chier, cgroup);
 	printf("Memory usage:\t%zuM / %zuM\n", usage / 1048576, limit / 1048576);
@@ -183,6 +208,11 @@ usage(void)
 void
 list(void)
 {
+	if (unlimited) {
+		fputs("List not available when computations are not limited.\n", stderr);
+		exit(EXIT_FAILURE);
+	}
+
 	pid_t *tasks;
 	int tasks_n = cgroup_task_list(chier, cgroup, &tasks);
 	if (tasks_n < 0)
@@ -203,7 +233,8 @@ main(int argc, char *argv[])
 		return EXIT_FAILURE;
 	}
 
-	if (!cgroup_available(chier, cgroup)) {
+	unlimited = access("/etc/compctl-unlimited", F_OK) >= 0;
+	if (!unlimited && !cgroup_available(chier, cgroup)) {
 		fputs("CGroup-based computation control is not available on this host.\n", stderr);
 		fputs("Most likely, this computer is not meant for computations,\n", stderr);
 		fputs("please consider switching to a different host.\n", stderr);

debian/changelog

+compctl (1.1-1) unstable; urgency=low
+
+  * Compctl client now works as simple server-less agent
+    if /etc/compctl-unlimited exists.
+
+ -- Petr Baudis <pasky@ucw.cz>  Thu, 12 Apr 2012 03:46:58 +0200
+
 compctl (1.0-1) unstable; urgency=low
 
   * Few further bugfixes, first production-ready release