[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v6] tools/xenconsoled: Increase file descriptor limit
2015-03-02 15:04 GMT+00:00 Andrew Cooper <andrew.cooper3@xxxxxxxxxx>: > 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, attempt to increase the limit. > > Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > Acked-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx> > Nothing against the patch but I think you should then check maximum number of pty on the system (ie http://www.cyberciti.biz/tips/howto-linux-increase-pty-session.html). Usually is high (like 4096) but still less than theory Xen domain limit (about 32k). This (in theory) would lead to domain0 with a not working interactive ssh. I would also be curious why the server always keeps slave descriptor open. Frediano > --- > v6: > * Fix 32bit build. (rlimit_t is an arch-specific width) > v5: > * Drop system maximum checking > * Unify set paths > v4: > * Calculate fd limit based on domid ABI - result is 132008 fds > * Warn if sufficient fds are not available. > v3: > * Hide Linux specific bits in #ifdef __linux__ > 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 | 38 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 38 insertions(+) > > diff --git a/tools/console/daemon/main.c b/tools/console/daemon/main.c > index 92d2fc4..11de5c9 100644 > --- a/tools/console/daemon/main.c > +++ b/tools/console/daemon/main.c > @@ -26,6 +26,7 @@ > #include <string.h> > #include <signal.h> > #include <sys/types.h> > +#include <sys/resource.h> > > #include "xenctrl.h" > > @@ -55,6 +56,41 @@ static void version(char *name) > printf("Xen Console Daemon 3.0\n"); > } > > +static void increase_fd_limit(void) > +{ > + /* > + * We require many file descriptors: > + * - per domain: pty master, pty slave, logfile and evtchn > + * - misc extra: hypervisor log, privcmd, gntdev, std... > + * > + * Allow a generous 1000 for misc, and calculate the maximum possible > + * number of fds which could be used. > + */ > + unsigned min_fds = (DOMID_FIRST_RESERVED * 4) + 1000; > + struct rlimit lim, new = { min_fds, min_fds }; > + > + if (getrlimit(RLIMIT_NOFILE, &lim) < 0) { > + fprintf(stderr, "Failed to obtain fd limit: %s\n", > + strerror(errno)); > + exit(1); > + } > + > + /* Do we already have sufficient? Great! */ > + if (lim.rlim_cur >= min_fds) > + return; > + > + /* Try to increase our limit. */ > + if (setrlimit(RLIMIT_NOFILE, &new) < 0) > + syslog(LOG_WARNING, > + "Unable to increase fd limit from {%llu, %llu} to " > + "{%llu, %llu}: (%s) - May run out with lots of > domains", > + (unsigned long long)lim.rlim_cur, > + (unsigned long long)lim.rlim_max, > + (unsigned long long)new.rlim_cur, > + (unsigned long long)new.rlim_max, > + strerror(errno)); > +} > + > int main(int argc, char **argv) > { > const char *sopts = "hVvit:o:"; > @@ -154,6 +190,8 @@ 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 > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxx > http://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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