From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: [PATCH v2] tools/xenconsoled: Increase file descriptor limit Date: Tue, 17 Feb 2015 16:21:24 +0000 Message-ID: <1424190084-9922-1-git-send-email-andrew.cooper3@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Xen-devel Cc: Andrew Cooper , Ian Jackson , Ian Campbell , Wei Liu List-Id: xen-devel@lists.xenproject.org XenServer's VM density testing uncovered a regression when moving from sysvinit to systemd where the file descriptor limit dropped from 4096 to 1024. (XenServer had previously inserted a ulimit statement into its initscripts.) One solution is to use LimitNOFILE=4096 in xenconsoled.service to match the lost ulimit, but that is only a stopgap solution. As Xenconsoled genuinely needs a large number of file descriptors if a large number of domains are running, and is well behaved with its descriptors, attempt to up the limit to the system maximum. Signed-off-by: Andrew Cooper CC: Ian Campbell CC: Ian Jackson CC: Wei Liu --- v2: * Always increase soft limit to hard limit * Correct commment regarding number of file descriptors * long -> unsigned long as that appears to be the underlying type of an rlim_t --- tools/console/daemon/main.c | 45 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/tools/console/daemon/main.c b/tools/console/daemon/main.c index 92d2fc4..0bb9d8a 100644 --- a/tools/console/daemon/main.c +++ b/tools/console/daemon/main.c @@ -26,6 +26,7 @@ #include #include #include +#include #include "xenctrl.h" @@ -55,6 +56,48 @@ static void version(char *name) printf("Xen Console Daemon 3.0\n"); } +/* + * Xenconsoled requires two file descriptors for each PV console (pty and log + * file), which can easily exceed the default of 1024 if many guests are + * running. Try to set the fd limit to the system maximum, falling back to a + * default of 4096. + */ +static void increase_fd_limit(void) +{ + FILE *fs_nr_open; + struct rlimit lim; + unsigned long nr_open = 4096; + + if (getrlimit(RLIMIT_NOFILE, &lim) < 0) + return; + + /* Increase the soft limit to the current hard limit. */ + if (lim.rlim_cur < lim.rlim_max) { + lim.rlim_cur = lim.rlim_max; + if (setrlimit(RLIMIT_NOFILE, &lim) < 0) + return; + } + + /* Attempt to locate the system maximum. */ + fs_nr_open = fopen("/proc/sys/fs/nr_open", "r"); + if (fs_nr_open) { + unsigned long nr; + + if (fscanf(fs_nr_open, "%lu", &nr) == 1) + nr_open = nr; + fclose(fs_nr_open); + } + + /* + * In the likely case that we are a root process with + * CAP_SYS_RESOURCE, attempt to up our hard limit. + */ + if (nr_open > lim.rlim_max) { + lim.rlim_cur = lim.rlim_max = nr_open; + setrlimit(RLIMIT_NOFILE, &lim); + } +} + int main(int argc, char **argv) { const char *sopts = "hVvit:o:"; @@ -154,6 +197,8 @@ int main(int argc, char **argv) openlog("xenconsoled", syslog_option, LOG_DAEMON); setlogmask(syslog_mask); + increase_fd_limit(); + if (!is_interactive) { daemonize(pidfile ? pidfile : "/var/run/xenconsoled.pid"); } -- 1.7.10.4