kvm.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Wanpeng Li <kernellwp@gmail.com>
To: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Paul Mackerras <paulus@ozlabs.org>,
	Ben Segall <bsegall@google.com>,
	Venkatesh Srinivas <venkateshs@chromium.org>,
	David Matlack <dmatlack@google.com>
Subject: Re: [PATCH 1/3] KVM: PPC: Book3S HV: exit halt polling on need_resched() as well
Date: Wed, 12 May 2021 08:02:02 +0800	[thread overview]
Message-ID: <CANRm+Cwq9F+yBTy8By0VgX3aA1NeVn0COAoRnYLr0jXe6QMOWA@mail.gmail.com> (raw)
In-Reply-To: <1620466310-8428-1-git-send-email-wanpengli@tencent.com>

Cc more guys,
On Sat, 8 May 2021 at 17:32, Wanpeng Li <kernellwp@gmail.com> wrote:
>
> From: Wanpeng Li <wanpengli@tencent.com>
>
> Inspired by commit 262de4102c7bb8 (kvm: exit halt polling on need_resched()
> as well), due to PPC implements an arch specific halt polling logic, we should
> add the need_resched() checking there as well.
>

Update the patch description:

Inspired by commit 262de4102c7bb8 (kvm: exit halt polling on need_resched()
as well), CFS_BANDWIDTH throttling will use resched_task() when there is just
one task to get the task to block. It was likely allowing VMs to overrun their
quota when halt polling. Due to PPC implements an arch specific halt polling
logic, we should add the need_resched() checking there as well.

> Cc: Paul Mackerras <paulus@ozlabs.org>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
>  arch/powerpc/kvm/book3s_hv.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 28a80d2..6199397 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -3936,7 +3936,8 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
>                                 break;
>                         }
>                         cur = ktime_get();
> -               } while (single_task_running() && ktime_before(cur, stop));
> +               } while (single_task_running() && !need_resched() &&
> +                        ktime_before(cur, stop));
>
>                 spin_lock(&vc->lock);
>                 vc->vcore_state = VCORE_INACTIVE;
> --
> 2.7.4
>

      parent reply	other threads:[~2021-05-12  0:02 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-08  9:31 Wanpeng Li
2021-05-08  9:31 ` [PATCH 2/3] KVM: X86: Bail out of direct yield in case of undercomitted scenarios Wanpeng Li
2021-05-11 21:44   ` Sean Christopherson
2021-05-12  2:43     ` Wanpeng Li
2021-05-12 16:59       ` Sean Christopherson
2021-05-08  9:31 ` [PATCH 3/3] KVM: X86: Fix vCPU preempted state from guest point of view Wanpeng Li
2021-05-11  0:18   ` Sean Christopherson
2021-05-11 10:28     ` Wanpeng Li
2021-05-12  0:02 ` Wanpeng Li [this message]

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=CANRm+Cwq9F+yBTy8By0VgX3aA1NeVn0COAoRnYLr0jXe6QMOWA@mail.gmail.com \
    --to=kernellwp@gmail.com \
    --cc=bsegall@google.com \
    --cc=dmatlack@google.com \
    --cc=jmattson@google.com \
    --cc=joro@8bytes.org \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=paulus@ozlabs.org \
    --cc=pbonzini@redhat.com \
    --cc=seanjc@google.com \
    --cc=venkateshs@chromium.org \
    --cc=vkuznets@redhat.com \
    --cc=wanpengli@tencent.com \
    --subject='Re: [PATCH 1/3] KVM: PPC: Book3S HV: exit halt polling on need_resched() as well' \
    /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).