[PATCH RFC 08/10] qemu_conf: Introduce a knob to turn off SCHED_CORE
Ideally, we would just pick the best default and users wouldn't
have to intervene at all. But in some cases it may be handy to
not bother with SCHED_CORE at all and thus let users turn the
feature off in qemu.conf.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/qemu/libvirtd_qemu.aug | 1 +
src/qemu/qemu.conf.in | 5 +++++
src/qemu/qemu_conf.c | 24 ++++++++++++++++++++++++
src/qemu/qemu_conf.h | 2 ++
src/qemu/test_libvirtd_qemu.aug.in | 1 +
5 files changed, 33 insertions(+)
diff --git a/src/qemu/libvirtd_qemu.aug b/src/qemu/libvirtd_qemu.aug
index 0f18775121..28a8db2b43 100644
--- a/src/qemu/libvirtd_qemu.aug
+++ b/src/qemu/libvirtd_qemu.aug
@@ -110,6 +110,7 @@ module Libvirtd_qemu =
| bool_entry "dump_guest_core"
| str_entry "stdio_handler"
| int_entry "max_threads_per_process"
+ | bool_entry "sched_core"
let device_entry = bool_entry "mac_filter"
| bool_entry "relaxed_acs_check"
diff --git a/src/qemu/qemu.conf.in b/src/qemu/qemu.conf.in
index 04b7740136..ece822edc3 100644
--- a/src/qemu/qemu.conf.in
+++ b/src/qemu/qemu.conf.in
@@ -952,3 +952,8 @@
# DO NOT use in production.
#
#deprecation_behavior = "none"
+
+# If this is set then QEMU and its threads will run with SCHED_CORE set,
+# meaning no other foreign process will share Hyper Threads of a single core
+# with QEMU nor with any of its helper process.
+#sched_core = 1
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index c22cf79cbe..03d8da0157 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -286,6 +286,8 @@ virQEMUDriverConfig *virQEMUDriverConfigNew(bool privileged,
cfg->deprecationBehavior = g_strdup("none");
+ cfg->schedCore = virProcessSchedCoreAvailable() == 1;
+
return g_steal_pointer(&cfg);
}
@@ -634,6 +636,8 @@ virQEMUDriverConfigLoadProcessEntry(virQEMUDriverConfig *cfg,
g_auto(GStrv) hugetlbfs = NULL;
g_autofree char *stdioHandler = NULL;
g_autofree char *corestr = NULL;
+ bool schedCore;
+ int rc;
size_t i;
if (virConfGetValueStringList(conf, "hugetlbfs_mount", true,
@@ -711,6 +715,26 @@ virQEMUDriverConfigLoadProcessEntry(virQEMUDriverConfig *cfg,
}
}
+ if ((rc = virConfGetValueBool(conf, "sched_core", &schedCore)) < 0)
{
+ return -1;
+ } else if (rc > 0) {
+ if (schedCore) {
+ int rv = virProcessSchedCoreAvailable();
+
+ if (rv < 0) {
+ virReportSystemError(errno, "%s",
+ _("Unable to detect SCHED_CORE"));
+ return -1;
+ } else if (rv == 0) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+ _("SCHED_CORE not supported by kernel"));
+ return -1;
+ }
+ }
+
+ cfg->schedCore = schedCore;
+ }
+
return 0;
}
diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
index c71a666aea..32899859c0 100644
--- a/src/qemu/qemu_conf.h
+++ b/src/qemu/qemu_conf.h
@@ -223,6 +223,8 @@ struct _virQEMUDriverConfig {
char **capabilityfilters;
char *deprecationBehavior;
+
+ bool schedCore;
};
G_DEFINE_AUTOPTR_CLEANUP_FUNC(virQEMUDriverConfig, virObjectUnref);
diff --git a/src/qemu/test_libvirtd_qemu.aug.in b/src/qemu/test_libvirtd_qemu.aug.in
index 757d21c33f..9f3f98d524 100644
--- a/src/qemu/test_libvirtd_qemu.aug.in
+++ b/src/qemu/test_libvirtd_qemu.aug.in
@@ -116,3 +116,4 @@ module Test_libvirtd_qemu =
{ "1" = "capname" }
}
{ "deprecation_behavior" = "none" }
+{ "sched_core" = "1" }
--
2.35.1