From: Paolo Bonzini <pbonzini@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>,
Eduardo Habkost <ehabkost@redhat.com>
Cc: "Wanpeng Li" <kernellwp@gmail.com>,
qemu-devel@nongnu.org, kvm@vger.kernel.org,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: Re: [Qemu-devel] [PATCH RESEND v2] i386/kvm: add support for KVM_CAP_X86_DISABLE_EXITS
Date: Wed, 16 May 2018 14:44:24 +0200 [thread overview]
Message-ID: <c4f7f4bd-80ce-3d84-fb0d-a7ac22333afd@redhat.com> (raw)
In-Reply-To: <20180512010007-mutt-send-email-mst@kernel.org>
On 12/05/2018 00:12, Michael S. Tsirkin wrote:
>> Maybe it's a better idea than overloading an option that is only
>> expected to control a CPUID bit.
> Well -realtime would be a bit confusing in that it enables mlock by
> default.
Currently, the only suboption of "-realtime" is mlock, which means that
the only three valid uses of it are
-realtime mlock=on
-realtime mlock=off
-realtime ''
We can change the default, I think. Only the third would change
meaning, and it's a slightly crazy way to use the option.
> From pure API point of view, hint-dedicated looks good since
> it seems to say "optimize for a dedicated host CPU" and
> it's a hint in that guests keep working if you violate this
> slightly once in a while.
>
> But I agree there's a problem: right now "kvm-" means "KVM PV"
> as opposed to e.g. HV enlightened gusts.
> So if you enable hyperv and also want to disable halt existing,
> what then? What should kvm-hint-dedicated=on do?
kvm-hint-dedicated=on only sets the CPUID bit, which Linux for example
uses that to disable pv spinlocks. "-realtime dedicated-cpus=on" only
disables the vmexits. You can use the two independently.
Thanks,
Paolo
> So how about a new hint-dedicated=on cpu flag? We can have that set
> kvm-hint-dedicated if kvm PV is enabled.
>
next prev parent reply other threads:[~2018-05-16 12:44 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-17 8:24 [Qemu-devel] [PATCH RESEND v2] i386/kvm: add support for KVM_CAP_X86_DISABLE_EXITS Wanpeng Li
2018-04-17 8:28 ` no-reply
2018-04-17 18:08 ` Michael S. Tsirkin
2018-04-18 1:09 ` Wanpeng Li
2018-05-11 21:57 ` Michael S. Tsirkin
2018-05-12 0:49 ` Wanpeng Li
2018-04-17 20:59 ` Eduardo Habkost
2018-04-18 1:20 ` Wanpeng Li
2018-04-19 15:48 ` Paolo Bonzini
2018-04-19 19:56 ` Eduardo Habkost
2018-04-19 21:32 ` Paolo Bonzini
2018-04-19 21:53 ` Eduardo Habkost
2018-05-11 22:12 ` Michael S. Tsirkin
2018-05-16 12:34 ` Eduardo Habkost
2018-05-16 14:26 ` Michael S. Tsirkin
2018-05-17 17:34 ` Eduardo Habkost
2018-05-17 17:57 ` Michael S. Tsirkin
2018-05-17 18:18 ` Eduardo Habkost
2018-05-16 12:44 ` Paolo Bonzini [this message]
2018-05-16 14:22 ` Michael S. Tsirkin
2018-05-16 15:04 ` Paolo Bonzini
2018-05-16 15:13 ` Michael S. Tsirkin
2018-05-16 15:33 ` Eduardo Habkost
2018-05-16 16:21 ` Michael S. Tsirkin
2018-05-16 17:20 ` Eduardo Habkost
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