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authorJan Kiszka <jan.kiszka@siemens.com>2012-04-24 18:40:17 +0400
committerMarcelo Tosatti <mtosatti@redhat.com>2012-04-28 02:40:29 +0400
commitb6ddf05ff68d81a7c1736717faf492b70e9bf4f9 (patch)
treedbcf0f64e8bd0e420a498b6d074b5f0d1afc91ed /Documentation/virtual
parent0589ff6c11d8128cf053c3ddc75b0f6d8b71c62b (diff)
downloadlinux-b6ddf05ff68d81a7c1736717faf492b70e9bf4f9.tar.xz
KVM: x86: Run PIT work in own kthread
We can't run PIT IRQ injection work in the interrupt context of the host timer. This would allow the user to influence the handler complexity by asking for a broadcast to a large number of VCPUs. Therefore, this work was pushed into workqueue context in 9d244caf2e. However, this prevents prioritizing the PIT injection over other task as workqueues share kernel threads. This replaces the workqueue with a kthread worker and gives that thread a name in the format "kvm-pit/<owner-process-pid>". That allows to identify and adjust the kthread priority according to the VM process parameters. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'Documentation/virtual')
-rw-r--r--Documentation/virtual/kvm/api.txt8
1 files changed, 8 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index a7cb93cb2154..eb62761b7683 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1810,6 +1810,14 @@ Valid flags are:
#define KVM_PIT_SPEAKER_DUMMY 1 /* emulate speaker port stub */
+PIT timer interrupts may use a per-VM kernel thread for injection. If it
+exists, this thread will have a name of the following pattern:
+
+kvm-pit/<owner-process-pid>
+
+When running a guest with elevated priorities, the scheduling parameters of
+this thread may have to be adjusted accordingly.
+
This IOCTL replaces the obsolete KVM_CREATE_PIT.