[vfio-users] CPU pinning with cgroups

Tue Sep 8 15:40:35 UTC 2015

While using directly the monitor you can plug / unplug usb from the vm
using a simple shell command...
Also, it is interesting in case your vm crash to be able to take back
control to host (using ssh + shell command from phone)

--
Deldycke Quentin

On 8 September 2015 at 17:01, Will Marler <will at wmarler.com> wrote:

> Ha! Interesting. Haven't tried that.
>
> On Tue, Sep 8, 2015 at 8:56 AM, Blank Field <ihatethisfield at gmail.com>
> wrote:
>
>> ...but wait, there's more!
>> If you unplug the p-t'd device from the host while VM is offline, the VM
>> will fail to boot.
>> There's still a lot of work to be done with USB.
>> On Sep 8, 2015 5:51 PM, "Will Marler" <will at wmarler.com> wrote:
>>
>>> USB pass-through works quite well with libvirt/virt-manager now; I've
>>> used it for mouse, keyboard, two different audio devices, while the guest
>>> was running. There's one feature request that I haven't gotten around to
>>> submitting; have an "enable/disable" checkbox in the virt-manager gui (I
>>> will not always want to p-t a USB device, but I will want to frequently
>>> enough that deleting it & re-adding it each time gets on my nerves).
>>>
>>> On Tue, Sep 8, 2015 at 12:15 AM, Quentin Deldycke <
>>> quentindeldycke at gmail.com> wrote:
>>>
>>>> My main problem with libvirt was:
>>>>
>>>>
>>>>    - no ovmf support at the time i created my vm on debian
>>>>    - No correct usb passthrough
>>>>
>>>>
>>>> The qemu monitor support the device_add command. Which let me bind /
>>>> unbind usb devices at runtime, without limit of number.
>>>>
>>>> I really love libvirt at my job, but for this particular case, i found
>>>> it less interesting..
>>>>
>>>>
>>>> --
>>>> Deldycke Quentin
>>>>
>>>>
>>>> On 8 September 2015 at 06:23, Will Marler <will at wmarler.com> wrote:
>>>>
>>>>> Not to mention, you can still see the actual qemu invocation script in
>>>>> the logs when you use libvirt, in case you *really* want to (though a
>>>>> pastebin share of your libvirt xml config is better, imo ...)
>>>>>
>>>>> On Mon, Sep 7, 2015 at 10:15 PM, Jon Panozzo <jonp at lime-technology.com
>>>>> > wrote:
>>>>>
>>>>>> Just to second Alex's point here, I see a lot of folks doing QEMU the
>>>>>> old fashioned way, which is to say, manual invocation.  Libvirt really is
>>>>>> an amazing management solution and makes things so much easier.  Lots of
>>>>>> things can go awry if you're invoking QEMU manually, and libvirt can
>>>>>> prevent that, as well as automate many other aspects of management that
>>>>>> manual QEMU invocation cannot.
>>>>>> On Sep 7, 2015 3:20 PM, "Alex Williamson" <
>>>>>> alex.l.williamson at gmail.com> wrote:
>>>>>>
>>>>>>> On Sun, Sep 6, 2015 at 7:19 PM, Garrett Powell <
>>>>>>> garretttracypowell at gmail.com> wrote:
>>>>>>>
>>>>>>>> I've been having trouble with my guest freezing up, which I'm told
>>>>>>>> is due to a lack of CPU pinning. I'm currently trying to set up CPU pinning
>>>>>>>> with cgroups (specifically cpuset), but the freezing isn't going away.
>>>>>>>> Could anyone tell me what I'm doing wrong? I'm specifically referring to
>>>>>>>> the *cgcreate*, *cgset *and* cgexec* lines. Here's my launch
>>>>>>>> script:
>>>>>>>>
>>>>>>>> #!/bin/bash
>>>>>>>>
>>>>>>>> export QEMU_AUDIO_DRV=pa
>>>>>>>> export QEMU_PA_SERVER=localhost
>>>>>>>> export PULSE_SERVER=localhost
>>>>>>>>
>>>>>>>> vfio-bind 0000:06:00.0
>>>>>>>>
>>>>>>>> synergys --daemon --config /etc/synergy.conf
>>>>>>>>
>>>>>>>> for i in {0..3}; do
>>>>>>>>     echo performance >
>>>>>>>> /sys/devices/system/cpu/cpu${i}/cpufreq/scaling_governor
>>>>>>>> done
>>>>>>>>
>>>>>>>> echo 5120 > /proc/sys/vm/nr_hugepages
>>>>>>>>
>>>>>>>> cgcreate -g cpuset:kvm
>>>>>>>> cgset -r cpuset.cpus=0-3 -r cpuset.mems=0 -r cpuset.cpu_exclusive=1
>>>>>>>> kvm
>>>>>>>> cgexec -g cpuset:kvm qemu-system-x86_64 \
>>>>>>>>
>>>>>>>
>>>>>>> Ok, so you've change to pCPUs 0-3 instead of 4-7, but doesn't this
>>>>>>> have the same problem as your previous attempt with taskset?  You're using
>>>>>>> a different tool, but afaict you're still not doing 1:1 pinning of vCPUs,
>>>>>>> you're pining them to a set of pCPUs.  Taskset can work, but you need to
>>>>>>> get the thread ID for each vCPU thread and pin it.  The problem is not the
>>>>>>> tool you're using but how you're using it, to set the entire process and
>>>>>>> all the threads it will launch to a range of CPUs rather than pulling out
>>>>>>> the vCPU threads and individually pinning them.  There's this really great
>>>>>>> tool that already does this, it's called libvirt.  Thanks,
>>>>>>>
>>>>>>> Alex
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> vfio-users mailing list
>>>>>>> vfio-users at redhat.com
>>>>>>> https://www.redhat.com/mailman/listinfo/vfio-users
>>>>>>>
>>>>>>>
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>>>>>>
>>>>>
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>>>>
>>>
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>
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