[vfio-users] CPU pinning with cgroups

[Will Marler]

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
>>>>>>
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>>>>>>
>>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>
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>>>
>>
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