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Date: Fri, 22 Jun 2018 15:22:36 -0300
From: Eduardo Habkost <ehabkost@redhat.com>
Message-ID: <20180622182236.GA7451@localhost.localdomain>
References: <20180622003140.164613-1-mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v4 1/2] kvm: support -overcommit
 cpu-pm=on|off
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <rth@twiddle.net>, Marcelo Tosatti <mtosatti@redhat.com>, kvm@vger.kernel.org

On Fri, Jun 22, 2018 at 03:31:48AM +0300, Michael S. Tsirkin wrote:
> With this flag, kvm allows guest to control host CPU power state.  This
> increases latency for other processes using same host CPU in an
> unpredictable way, but if decreases idle entry/exit times for the
> running VCPU, so to use it QEMU needs a hint about whether host CPU is
> overcommitted, hence the flag name.

The flag name in the code below is still "-dedicated".

[...]
> +static QemuOptsList qemu_dedicated_opts = {
> +    .name = "dedicated",
[...]
> +            case QEMU_OPTION_dedicated:
> +                opts = qemu_opts_parse_noisily(qemu_find_opts("dedicated"),
> +                                               optarg, false);
[...]
> +DEF("dedicated", HAS_ARG, QEMU_OPTION_dedicated,
> +    "-dedicated [mem-lock=on|off][cpu-pm=on|off]\n"
> +    "                run qemu with realtime features\n"
> +    "                mem-lock=on|off controls memory lock support (default: off)\n"
> +    "                cpu-pm=on|off controls cpu power management (default: off)\n",
> +    QEMU_ARCH_ALL)
> +STEXI
> +@item -dedicated mem-lock=on|off
> +@item -dedicated cpu-pm=on|off
> +@findex -dedicated
> +Run qemu using dedicated host resources.
> +Locking qemu and guest memory can be enabled via @option{mem-lock=on}
> +(disabled by default). This is equivalent to @option{realtime}.
> +Guest ability to manage power state of host cpus (increasing latency for other
> +processes on the same host cpu, but decreasing latency for guest)
> +can be enabled via @option{cpu-pm=on} (disabled by default).
> +ETEXI
[...]

-- 
Eduardo