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qemu: Add support for overriding max threads per process limit

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Some VM configurations may result in a large number of threads created by
the associated qemu process which can exceed the system default limit. The
maximum number of threads allowed per process is controlled by the pids
cgroup controller and is set to 16k when creating VMs with systemd's
machined service. The maximum number of threads per process is recorded
in the pids.max file under the machine's pids controller cgroup hierarchy,
e.g.

$cgrp-mnt/pids/machine.slice/machine-qemu\\x2d1\\x2dtest.scope/pids.max

Maximum threads per process is controlled with the TasksMax property of
the systemd scope for the machine. This patch adds an option to qemu.conf
which can be used to override the maximum number of threads allowed per
qemu process. If the value of option is greater than zero, it will be set
in the TasksMax property of the machine's scope after creating the machine.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Jim Fehlig 2019-05-22 17:12:14 -06:00
parent 4837328d68
commit d5572f62e3
12 changed files with 54 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
src/lxc/lxc_cgroup.c
View File

@ -455,6 +455,7 @@ virCgroupPtr virLXCCgroupCreate(virDomainDefPtr def,
nnicindexes, nicindexes,
def->resource->partition,
-1,
0,
&cgroup) < 0)
goto cleanup;

1
src/qemu/libvirtd_qemu.aug
View File

@ -95,6 +95,7 @@ module Libvirtd_qemu =
| limits_entry "max_core"
| bool_entry "dump_guest_core"
| str_entry "stdio_handler"
| int_entry "max_threads_per_process"
let device_entry = bool_entry "mac_filter"
| bool_entry "relaxed_acs_check"

10
src/qemu/qemu.conf
View File

@ -613,6 +613,16 @@
#max_processes = 0
#max_files = 0
# If max_threads_per_process is set to a positive integer, libvirt
# will use it to set the maximum number of threads that can be
# created by a qemu process. Some VM configurations can result in
# qemu processes with tens of thousands of threads. systemd-based
# systems typically limit the number of threads per process to
# 16k. max_threads_per_process can be used to override default
# limits in the host OS.
#
#max_threads_per_process = 0
# If max_core is set to a non-zero integer, then QEMU will be
# permitted to create core dumps when it crashes, provided its
# RAM size is smaller than the limit set.

1
src/qemu/qemu_cgroup.c
View File

@ -929,6 +929,7 @@ qemuInitCgroup(virDomainObjPtr vm,
nnicindexes, nicindexes,
vm->def->resource->partition,
cfg->cgroupControllers,
cfg->maxThreadsPerProc,
&priv->cgroup) < 0) {
if (virCgroupNewIgnoreError())
goto done;

2
src/qemu/qemu_conf.c
View File

@ -670,6 +670,8 @@ virQEMUDriverConfigLoadProcessEntry(virQEMUDriverConfigPtr cfg,
return -1;
if (virConfGetValueUInt(conf, "max_files", &cfg->maxFiles) < 0)
return -1;
if (virConfGetValueUInt(conf, "max_threads_per_process", &cfg->maxThreadsPerProc) < 0)
return -1;
if (virConfGetValueType(conf, "max_core") == VIR_CONF_STRING) {
if (virConfGetValueString(conf, "max_core", &corestr) < 0)

1
src/qemu/qemu_conf.h
View File

@ -162,6 +162,7 @@ struct _virQEMUDriverConfig {
unsigned int maxProcesses;
unsigned int maxFiles;
unsigned int maxThreadsPerProc;
unsigned long long maxCore;
bool dumpGuestCore;

1
src/qemu/test_libvirtd_qemu.aug.in
View File

@ -76,6 +76,7 @@ module Test_libvirtd_qemu =
{ "set_process_name" = "1" }
{ "max_processes" = "0" }
{ "max_files" = "0" }
{ "max_threads_per_process" = "0" }
{ "max_core" = "unlimited" }
{ "dump_guest_core" = "1" }
{ "mac_filter" = "1" }

6
src/util/vircgroup.c
View File

@ -1118,6 +1118,7 @@ virCgroupNewMachineSystemd(const char *name,
int *nicindexes,
const char *partition,
int controllers,
unsigned int maxthreads,
virCgroupPtr *group)
{
int rv;
@ -1134,7 +1135,8 @@ virCgroupNewMachineSystemd(const char *name,
isContainer,
nnicindexes,
nicindexes,
partition)) < 0)
partition,
maxthreads)) < 0)
return rv;
if (controllers != -1)
@ -1246,6 +1248,7 @@ virCgroupNewMachine(const char *name,
int *nicindexes,
const char *partition,
int controllers,
unsigned int maxthreads,
virCgroupPtr *group)
{
int rv;
@ -1262,6 +1265,7 @@ virCgroupNewMachine(const char *name,
nicindexes,
partition,
controllers,
maxthreads,
group)) == 0)
return 0;

1
src/util/vircgroup.h
View File

@ -98,6 +98,7 @@ int virCgroupNewMachine(const char *name,
int *nicindexes,
const char *partition,
int controllers,
unsigned int maxthreads,
virCgroupPtr *group)
ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2)
ATTRIBUTE_NONNULL(3);

24
src/util/virsystemd.c
View File

@ -252,12 +252,14 @@ int virSystemdCreateMachine(const char *name,
bool iscontainer,
size_t nnicindexes,
int *nicindexes,
const char *partition)
const char *partition,
unsigned int maxthreads)
{
int ret;
DBusConnection *conn;
char *creatorname = NULL;
char *slicename = NULL;
char *scopename = NULL;
static int hasCreateWithNetwork = 1;
if ((ret = virSystemdHasMachined()) < 0)
@ -403,11 +405,31 @@ int virSystemdCreateMachine(const char *name,
goto cleanup;
}
if (maxthreads > 0) {
if (!(scopename = virSystemdMakeScopeName(name, drivername, false)))
goto cleanup;
if (virDBusCallMethod(conn,
NULL,
NULL,
"org.freedesktop.systemd1",
"/org/freedesktop/systemd1",
"org.freedesktop.systemd1.Manager",
"SetUnitProperties",
"sba(sv)",
scopename,
true,
1,
"TasksMax", "t", (uint64_t)maxthreads) < 0)
goto cleanup;
}
ret = 0;
cleanup:
VIR_FREE(creatorname);
VIR_FREE(slicename);
VIR_FREE(scopename);
return ret;
}

3
src/util/virsystemd.h
View File

@ -50,7 +50,8 @@ int virSystemdCreateMachine(const char *name,
bool iscontainer,
size_t nnicindexes,
int *nicindexes,
const char *partition);
const char *partition,
unsigned int maxthreads);
int virSystemdTerminateMachine(const char *name);

12
tests/virsystemdtest.c
View File

@ -175,7 +175,7 @@ static int testCreateContainer(const void *opaque ATTRIBUTE_UNUSED)
123,
true,
0, NULL,
"highpriority.slice") < 0) {
"highpriority.slice", 0) < 0) {
fprintf(stderr, "%s", "Failed to create LXC machine\n");
return -1;
}
@ -208,7 +208,7 @@ static int testCreateMachine(const void *opaque ATTRIBUTE_UNUSED)
123,
false,
0, NULL,
NULL) < 0) {
NULL, 0) < 0) {
fprintf(stderr, "%s", "Failed to create KVM machine\n");
return -1;
}
@ -245,7 +245,7 @@ static int testCreateNoSystemd(const void *opaque ATTRIBUTE_UNUSED)
123,
false,
0, NULL,
NULL)) == 0) {
NULL, 0)) == 0) {
unsetenv("FAIL_NO_SERVICE");
fprintf(stderr, "%s", "Unexpected create machine success\n");
return -1;
@ -279,7 +279,7 @@ static int testCreateSystemdNotRunning(const void *opaque ATTRIBUTE_UNUSED)
123,
false,
0, NULL,
NULL)) == 0) {
NULL, 0)) == 0) {
unsetenv("FAIL_NOT_REGISTERED");
fprintf(stderr, "%s", "Unexpected create machine success\n");
return -1;
@ -313,7 +313,7 @@ static int testCreateBadSystemd(const void *opaque ATTRIBUTE_UNUSED)
123,
false,
0, NULL,
NULL)) == 0) {
NULL, 0)) == 0) {
unsetenv("FAIL_BAD_SERVICE");
fprintf(stderr, "%s", "Unexpected create machine success\n");
return -1;
@ -348,7 +348,7 @@ static int testCreateNetwork(const void *opaque ATTRIBUTE_UNUSED)
123,
true,
nnicindexes, nicindexes,
"highpriority.slice") < 0) {
"highpriority.slice", 0) < 0) {
fprintf(stderr, "%s", "Failed to create LXC machine\n");
return -1;
}