lkml.org 
[lkml]   [2016]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] kvm: cap halt polling at exactly halt_poll_ns
From
Date


On 09/03/2016 01:19, David Matlack wrote:
> When growing halt-polling, there is no check that the poll time exceeds
> the limit. It's possible for vcpu->halt_poll_ns grow once past
> halt_poll_ns, and stay there until a halt which takes longer than
> vcpu->halt_poll_ns. For example, booting a Linux guest with
> halt_poll_ns=11000:
>
> ... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 0 (shrink 10000)
> ... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 10000 (grow 0)
> ... kvm:kvm_halt_poll_ns: vcpu 0: halt_poll_ns 20000 (grow 10000)
>
> Signed-off-by: David Matlack <dmatlack@google.com>
> ---
> virt/kvm/kvm_main.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index a11cfd2..9102ae1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1952,6 +1952,9 @@ static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
> else
> val *= halt_poll_ns_grow;
>
> + if (val > halt_poll_ns)
> + val = halt_poll_ns;
> +
> vcpu->halt_poll_ns = val;
> trace_kvm_halt_poll_ns_grow(vcpu->vcpu_id, val, old);
> }
>

Applied to kvm/master, thanks.

Paolo

\
 
 \ /
  Last update: 2016-03-09 12:21    [W:0.044 / U:0.348 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site