[pve-devel] [PATCH kernel] By default disable the new dynamic halt polling behavior

[Alexandre DERUMIER]

>>Does upstream know about this? 

I don't have seen any report.

Maybe could we try to contact paolo bonzini from redhat.


----- Mail original -----
De: "Stefan Priebe" <s.priebe at profihost.ag>
À: "pve-devel" <pve-devel at pve.proxmox.com>
Envoyé: Vendredi 13 Mai 2016 07:52:05
Objet: Re: [pve-devel] [PATCH kernel] By default disable the new dynamic	halt polling behavior

Does upstream know about this? 

Stefan 

Excuse my typo sent from my mobile phone. 

> Am 12.05.2016 um 12:51 schrieb Wolfgang Bumiller <w.bumiller at proxmox.com>: 
> 
> The default behavior introduced by kernel commit aca6ff29c 
> (KVM: dynamic halt-polling) causes a spike in cpu usage and 
> massive performance degradation with virtio network under 
> network load. This patch changes the newly introduced kvm 
> module parameters to reflect the old behavior. 
> --- 
> Makefile | 1 + 
> kvm-dynamic-halt-polling-disable-default.patch | 12 ++++++++++++ 
> 2 files changed, 13 insertions(+) 
> create mode 100644 kvm-dynamic-halt-polling-disable-default.patch 
> 
> diff --git a/Makefile b/Makefile 
> index 5851d9d..7fb83d5 100644 
> --- a/Makefile 
> +++ b/Makefile 
> @@ -242,6 +242,7 @@ ${KERNEL_SRC}/README ${KERNEL_CFG_ORG}: ${KERNELSRCTAR} 
> cd ${KERNEL_SRC}; patch -p1 < ../CVE-2016-4485-net-fix-infoleak-in-llc.patch 
> cd ${KERNEL_SRC}; patch -p1 < ../CVE-2016-4486-net-fix-infoleak-in-rtnetlink.patch 
> cd ${KERNEL_SRC}; patch -p1 < ../CVE-2016-4558-bpf-fix-refcnt-overflow.patch 
> + cd ${KERNEL_SRC}; patch -p1 < ../kvm-dynamic-halt-polling-disable-default.patch 
> sed -i ${KERNEL_SRC}/Makefile -e 's/^EXTRAVERSION.*$$/EXTRAVERSION=${EXTRAVERSION}/' 
> touch $@ 
> 
> diff --git a/kvm-dynamic-halt-polling-disable-default.patch b/kvm-dynamic-halt-polling-disable-default.patch 
> new file mode 100644 
> index 0000000..dcf1dee 
> --- /dev/null 
> +++ b/kvm-dynamic-halt-polling-disable-default.patch 
> @@ -0,0 +1,12 @@ 
> +diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c 
> +--- a/virt/kvm/kvm_main.c 2016-05-12 10:39:37.540387127 +0200 
> ++++ b/virt/kvm/kvm_main.c 2016-05-04 10:43:38.063996221 +0200 
> +@@ -71,7 +71,7 @@ static unsigned int halt_poll_ns = KVM_H 
> + module_param(halt_poll_ns, uint, S_IRUGO | S_IWUSR); 
> + 
> + /* Default doubles per-vcpu halt_poll_ns. */ 
> +-static unsigned int halt_poll_ns_grow = 2; 
> ++static unsigned int halt_poll_ns_grow = 0; 
> + module_param(halt_poll_ns_grow, int, S_IRUGO); 
> + 
> + /* Default resets per-vcpu halt_poll_ns . */ 
> -- 
> 2.1.4 
> 
> 
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