Date: Sun, 11 Jun 2017 11:51:21 +0200 From: Harry Schmalzbauer <freebsd@omnilan.de> To: Anish <akgupt3@gmail.com> Cc: "freebsd-virtualization@freebsd.org" <freebsd-virtualization@freebsd.org> Subject: Re: PCIe passthrough really that expensive? Message-ID: <593D1299.3030402@omnilan.de> In-Reply-To: <593A5AB1.7090301@omnilan.de> References: <59383F5C.8020801@omnilan.de> <CALnRwMRst1d_O_ix-_JaS=tH8=dPtNNkDo9WyzRH1_nBi1N6zA@mail.gmail.com> <593A5AB1.7090301@omnilan.de>
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Bezüglich Harry Schmalzbauer's Nachricht vom 09.06.2017 10:22 (localtime): > Bezüglich Anish's Nachricht vom 08.06.2017 14:35 (localtime): >> Hi Harry, >>> I thought I'd save these expensive VM_Exits by using the passthru path. >> Completely wrong, is it? >> >> It depends on which processor you are using. For example APICv was >> introduced in IvyBridge which enabled h/w assisted localAPIC rather than >> using s/w emulated, bhyve supports it on Intel processors. … > I'm still usign IvyBridge (E3v2) with this "new" machine, but haven't > ever heard/thought about APCIv! It seems APICv is available on IvyBridge-EP (Xeon E5/E7v2) only, not for E3v2 :-( Furthermore, if I didn't miss anything in the datasheets, no currently available E3 Xeon offers local APIC virtualization. Can somebody of the xperts confirm that? … >> Can you run a simple experiment, assign pptdev interrupts to core that's >> not running guest/vcpu? This will reduce #VMEXIT on vcpu which we know >> is expensive. > Interesting approach. But I have no idea how I should assign a PCIe > specific core to a PCIe dev. Is it pptdev specific? The tunables in > device.hints(5) can't be used for that, can they? I wasn't able to find out how to do that. Any hints highly appreciated! -harry
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