diff mbox series

KVM: make uevents configurable

Message ID 20241122095806.4034415-1-bk@alpico.io (mailing list archive)
State New
Headers show
Series KVM: make uevents configurable | expand

Commit Message

Bernhard Kauer Nov. 22, 2024, 9:58 a.m. UTC 
Handling of uevents in userlevel is a bottleneck for tiny VMs.

Running 10_000 VMs keeps one and a half cores busy for 5.4 seconds to let
systemd-udevd handle all messages.  That is roughly 27x longer than
the 0.2 seconds needed for running the VMs without them.

We choose a read-only module parameter here due to its simplicity and
ease of maintenance.

Signed-off-by: Bernhard Kauer <bk@alpico.io>
---
 virt/kvm/kvm_main.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 609e0bd68e8e..6139cd67a96a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -97,6 +97,9 @@  EXPORT_SYMBOL_GPL(halt_poll_ns_shrink);
 bool debugfs_per_vm = true;
 module_param(debugfs_per_vm, bool, 0644);
 
+bool disable_uevent_notify;
+module_param(disable_uevent_notify, bool, 0444);
+
 /*
  * Ordering of locks:
  *
@@ -6276,7 +6279,7 @@  static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
 	struct kobj_uevent_env *env;
 	unsigned long long created, active;
 
-	if (!kvm_dev.this_device || !kvm)
+	if (!kvm_dev.this_device || !kvm || disable_uevent_notify)
 		return;
 
 	mutex_lock(&kvm_lock);