| Message ID | 20231218101340.35053-1-f.ebner@proxmox.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] qemu_init: increase NOFILE soft limit on POSIX | expand |
On Mon, Dec 18, 2023 at 11:13:40AM +0100, Fiona Ebner wrote: > In many configurations, e.g. multiple vNICs with multiple queues or > with many Ceph OSDs, the default soft limit of 1024 is not enough. > QEMU is supposed to work fine with file descriptors >= 1024 and does > not use select() on POSIX. Bump the soft limit to the allowed hard > limit to avoid issues with the aforementioned configurations. > > Of course the limit could be raised from the outside, but the man page > of systemd.exec states about 'LimitNOFILE=': > > > Don't use. > > [...] > > Typically applications should increase their soft limit to the hard > > limit on their own, if they are OK with working with file > > descriptors above 1023, > > If the soft limit is already the same as the hard limit, avoid the > superfluous setrlimit call. This can avoid a warning with a strict > seccomp filter blocking setrlimit if NOFILE was already raised before > executing QEMU. > > Buglink: https://bugzilla.proxmox.com/show_bug.cgi?id=4507 > Signed-off-by: Fiona Ebner <f.ebner@proxmox.com> > --- Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> With regards, Daniel
Am 18.12.23 um 11:13 schrieb Fiona Ebner: > In many configurations, e.g. multiple vNICs with multiple queues or > with many Ceph OSDs, the default soft limit of 1024 is not enough. > QEMU is supposed to work fine with file descriptors >= 1024 and does > not use select() on POSIX. Bump the soft limit to the allowed hard > limit to avoid issues with the aforementioned configurations. > > Of course the limit could be raised from the outside, but the man page > of systemd.exec states about 'LimitNOFILE=': > >> Don't use. >> [...] >> Typically applications should increase their soft limit to the hard >> limit on their own, if they are OK with working with file >> descriptors above 1023, > > If the soft limit is already the same as the hard limit, avoid the > superfluous setrlimit call. This can avoid a warning with a strict > seccomp filter blocking setrlimit if NOFILE was already raised before > executing QEMU. > > Buglink: https://bugzilla.proxmox.com/show_bug.cgi?id=4507 > Signed-off-by: Fiona Ebner <f.ebner@proxmox.com> > --- > Ping
On Fri, Feb 02, 2024 at 09:35:19AM +0100, Fiona Ebner wrote: > Am 18.12.23 um 11:13 schrieb Fiona Ebner: > > In many configurations, e.g. multiple vNICs with multiple queues or > > with many Ceph OSDs, the default soft limit of 1024 is not enough. > > QEMU is supposed to work fine with file descriptors >= 1024 and does > > not use select() on POSIX. Bump the soft limit to the allowed hard > > limit to avoid issues with the aforementioned configurations. > > > > Of course the limit could be raised from the outside, but the man page > > of systemd.exec states about 'LimitNOFILE=': > > > >> Don't use. > >> [...] > >> Typically applications should increase their soft limit to the hard > >> limit on their own, if they are OK with working with file > >> descriptors above 1023, > > > > If the soft limit is already the same as the hard limit, avoid the > > superfluous setrlimit call. This can avoid a warning with a strict > > seccomp filter blocking setrlimit if NOFILE was already raised before > > executing QEMU. > > > > Buglink: https://bugzilla.proxmox.com/show_bug.cgi?id=4507 > > Signed-off-by: Fiona Ebner <f.ebner@proxmox.com> > > --- > > > > Ping I have this queued already for my next pull request With regards, Daniel
diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h index dff32ae185..b881ac6c6f 100644 --- a/include/sysemu/os-posix.h +++ b/include/sysemu/os-posix.h @@ -51,6 +51,7 @@ bool is_daemonized(void); void os_daemonize(void); bool os_set_runas(const char *user_id); void os_set_chroot(const char *path); +void os_setup_limits(void); void os_setup_post(void); int os_mlock(void); diff --git a/include/sysemu/os-win32.h b/include/sysemu/os-win32.h index 1047d260cb..106f155037 100644 --- a/include/sysemu/os-win32.h +++ b/include/sysemu/os-win32.h @@ -128,6 +128,11 @@ static inline int os_mlock(void) return -ENOSYS; } +void os_setup_limits(void) +{ + return; +} + #define fsync _commit #if !defined(lseek) diff --git a/os-posix.c b/os-posix.c index 52ef6990ff..a4284e2c07 100644 --- a/os-posix.c +++ b/os-posix.c @@ -24,6 +24,7 @@ */ #include "qemu/osdep.h" +#include <sys/resource.h> #include <sys/wait.h> #include <pwd.h> #include <grp.h> @@ -256,6 +257,27 @@ void os_daemonize(void) } } +void os_setup_limits(void) +{ + struct rlimit nofile; + + if (getrlimit(RLIMIT_NOFILE, &nofile) < 0) { + warn_report("unable to query NOFILE limit: %s", strerror(errno)); + return; + } + + if (nofile.rlim_cur == nofile.rlim_max) { + return; + } + + nofile.rlim_cur = nofile.rlim_max; + + if (setrlimit(RLIMIT_NOFILE, &nofile) < 0) { + warn_report("unable to set NOFILE limit: %s", strerror(errno)); + return; + } +} + void os_setup_post(void) { int fd = 0; diff --git a/system/vl.c b/system/vl.c index 2bcd9efb9a..6f42f37200 100644 --- a/system/vl.c +++ b/system/vl.c @@ -2774,6 +2774,8 @@ void qemu_init(int argc, char **argv) error_init(argv[0]); qemu_init_exec_dir(argv[0]); + os_setup_limits(); + qemu_init_arch_modules(); qemu_init_subsystems();