LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Rik van Riel <riel@redhat.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Avi Kiviti <avi@redhat.com>,
	Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Mike Galbraith <efault@gmx.de>,
	Chris Wright <chrisw@sous-sol.org>,
	"Nakajima, Jun" <jun.nakajima@intel.com>
Subject: [PATCH -v8 6/7] kvm: keep track of which task is running a KVM vcpu
Date: Mon, 31 Jan 2011 16:47:01 -0500	[thread overview]
Message-ID: <20110131164701.28da2ed1@annuminas.surriel.com> (raw)
In-Reply-To: <20110131164049.0ad68e72@annuminas.surriel.com>

Keep track of which task is running a KVM vcpu.  This helps us
figure out later what task to wake up if we want to boost a
vcpu that got preempted.

Unfortunately there are no guarantees that the same task
always keeps the same vcpu, so we can only track the task
across a single "run" of the vcpu.

Signed-off-by: Rik van Riel <riel@redhat.com>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a055742..9d56ed5 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -81,6 +81,7 @@ struct kvm_vcpu {
 #endif
 	int vcpu_id;
 	struct mutex mutex;
+	struct pid *pid;
 	int   cpu;
 	atomic_t guest_mode;
 	struct kvm_run *run;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5225052..0fa9a48 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -117,6 +117,14 @@ void vcpu_load(struct kvm_vcpu *vcpu)
 	int cpu;
 
 	mutex_lock(&vcpu->mutex);
+	if (unlikely(vcpu->pid != current->pids[PIDTYPE_PID].pid)) {
+		/* The thread running this VCPU changed. */
+		struct pid *oldpid = vcpu->pid;
+		struct pid *newpid = get_task_pid(current, PIDTYPE_PID);
+		rcu_assign_pointer(vcpu->pid, newpid);
+		synchronize_rcu();
+		put_pid(oldpid);
+	}
 	cpu = get_cpu();
 	preempt_notifier_register(&vcpu->preempt_notifier);
 	kvm_arch_vcpu_load(vcpu, cpu);
@@ -185,6 +193,7 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
 	vcpu->cpu = -1;
 	vcpu->kvm = kvm;
 	vcpu->vcpu_id = id;
+	vcpu->pid = NULL;
 	init_waitqueue_head(&vcpu->wq);
 
 	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
@@ -208,6 +217,7 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_init);
 
 void kvm_vcpu_uninit(struct kvm_vcpu *vcpu)
 {
+	put_pid(vcpu->pid);
 	kvm_arch_vcpu_uninit(vcpu);
 	free_page((unsigned long)vcpu->run);
 }


  parent reply	other threads:[~2011-01-31 21:48 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-31 21:40 [PATCH -v8 0/7] directed yield for Pause Loop Exiting Rik van Riel
2011-01-31 21:41 ` [PATCH -v8 1/7] sched: check the right ->nr_running in yield_task_fair Rik van Riel
2011-01-31 21:42 ` [PATCH -v8 2/7] sched: limit the scope of clear_buddies Rik van Riel
2011-01-31 21:43 ` [PATCH -v8 3/7] sched: use a buddy to implement yield_task_fair Rik van Riel
2011-01-31 21:44 ` [PATCH -v8 4/7] sched: Add yield_to(task, preempt) functionality Rik van Riel
2011-01-31 21:46 ` [PATCH -v8 5/7] export pid symbols needed for kvm_vcpu_on_spin Rik van Riel
2011-01-31 21:47 ` Rik van Riel [this message]
2011-01-31 21:47 ` [PATCH -v8 7/7] kvm: use yield_to instead of sleep in kvm_vcpu_on_spin Rik van Riel
2011-02-01 10:53 ` [PATCH -v8 0/7] directed yield for Pause Loop Exiting Peter Zijlstra
2011-02-01 14:34   ` Rik van Riel

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20110131164701.28da2ed1@annuminas.surriel.com \
    --to=riel@redhat.com \
    --cc=a.p.zijlstra@chello.nl \
    --cc=avi@redhat.com \
    --cc=chrisw@sous-sol.org \
    --cc=efault@gmx.de \
    --cc=jun.nakajima@intel.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=vatsa@linux.vnet.ibm.com \
    --subject='Re: [PATCH -v8 6/7] kvm: keep track of which task is running a KVM vcpu' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).