like I saw the reason for that but I have no idea why this
after running "virsh start VM2" I saw on VM1 a swapper
thread running for a lot of time causing this delay and
another thing when I checked "top" before and after I saw a
drop in a free RAM memory and increase in a SWAP available
memory (both by ~100M). this explains why the swapper showed
how can you explain such behavior if I have totally isolated
VMs running with 4G RAM each when on the HOST I have ~60G of
free RAM space? Is it possible that both QEMUs try to
allocate a shared memory region in HOSTs RAM that causes
such interference ?
Sent: Tuesday, July 26, 2016 12:24 PM
To: address@hidden; Yan Fridland
Subject: Re: [Qemu-discuss] [problem]-starting a
VM causes RT (latency) problem for application running
on another VM
On 2016年07月26日 15:48, Yan
a lot for your comment.
I am doing emulator pin to the QEMU process in the XML:
<vcpupin vcpu='0' cpuset='1'/>
<vcpupin vcpu='1' cpuset='2'/>
<vcpupin vcpu='2' cpuset='3'/>
<vcpusched vcpus='1-2' scheduler='fifo'
looks like it doesn’t help. Is there any way to make ALL
the related QEMU threads run within the scope of cores
1,2,3,8 ONLY in the above example?
it is so wired, I have no better ways to handle it since I
have no experienced the similar issue as your. so, just two
suggestion for you:
1: check all qemu thread associated entries under cgroup
filesystem, sure that cpusets are correctly set.
2: if 1 fails, it may means there is nothing left to do,
ftrace for schduler.
whatever result, let me know please. I am very interesting in
Sent: Tuesday, July 26, 2016 6:12 AM
To: Yan Fridland; address@hidden
Subject: Re: [Qemu-discuss] [problem]-starting
a VM causes RT (latency) problem for application
running on another VM
On 2016年07月25日 23:03, Yan
Here is a problem I saw when
I ran virsh start to a VM.
I have 2VMs on a server when
one of them is running a RT application and the other
is in shut down state. Then I executed "virsh start"
to the second VM and saw 2-3 seconds later a big
latency problem in my RT application running on the
I want to emphasize that the
VMs use dedicated isolated cores of the server and I
have the relevant configuration on the server and the
vcpu pinning section of virsh xml.
Can anyone tell me why I
experience such behavior and how it can be resolved?
I will highly appreciate your
I am not
very sure, but I suggest you to add emulatorpin in xml file,
then see results. actually, all qemu associated process can
use all processors via cgroup configure created by libvirt,