Date: Sun, 5 May 2019 13:29:13 +0000 From: "Bapat, Udayan" <Udayan.Bapat@netapp.com> To: Anish <akgupt3@gmail.com>, Harry Schmalzbauer <freebsd@omnilan.de> Cc: "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: BSD11 vs BSD12 KVM performance Message-ID: <1C0C46D0-7B1A-46AF-A354-B210EB2D0D2F@netapp.com> In-Reply-To: <CALnRwMSAje_SWxWPk%2BaHcJH3gjXaWoQbjHnUMkKkLdZjiAyPBA@mail.gmail.com> References: <D2BA45B3-5156-424F-A74A-C41FE0E20CEC@netapp.com> <b83b1234-6359-2b26-d9ce-9eb261861eda@omnilan.de> <CALnRwMSAje_SWxWPk%2BaHcJH3gjXaWoQbjHnUMkKkLdZjiAyPBA@mail.gmail.com>
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Thanks for the responses. My bad. I meant BSD10 vs BSD11 and not 11 vs 12. Also I am not doing any migration. This is purely a normal runtime behavior difference. We have enabled all the host hypervisor VM-x best practices. So could you please clarify what you mean by “intercepts always enabled”? From: Anish <akgupt3@gmail.com> Date: Saturday, May 4, 2019 at 8:54 PM Cc: "Bapat, Udayan" <Udayan.Bapat@netapp.com>, "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: BSD11 vs BSD12 KVM performance NetApp Security WARNING: This is an external email. Do not click links or open attachments unless you recognize the sender and know the content is safe. Hi Udayan, Intel VM-x and AMD SVM allow hypervisor to intercept TSC access for save/restore of VM migration, so when these intercepts are enabled, rdtsc will require switch between root and non-root mode which is expensive and may cost few hundreds of cpu cycles. Is it possible that one has these intercepts always enabled even when migration is not started? -Anish
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