Re: vCPU scalability for linux VMs
On Wednesday, May 5, 2010 at 01:53:55 -0400, Srivatsa Vaddagiri wrote: On Wed, May 05, 2010 at 12:31:11PM -0700, Alec Istomin wrote: On Wednesday, May 5, 2010 at 13:27:39 -0400, Srivatsa Vaddagiri wrote: My preliminary results show that single vCPU Linux VMs perform up to 10 times better than 4vCPU Linux VMs (consolidated performance of 8 VMs on 8 core pre-Nehalem server). I suspect that I'm missing something major and look for any means that can help improve SMP VMs performance. Could you provide more details of what workload was used to compare this performance? It's Dell's DVD-Store LAMP stack test suite with Medium database (about 1 GB MySQL data) . 8x 2Gb VMs (on 16GB RAM host) with different vCPU configuration simultaneously loaded by external web clients. Ok ..Do you have any more data on how the vCPU scalability looks like (how the throughput scales with increasing vCPUs)? See attached for 1 vs 2 vs 4 vCPUs consolidated throughput from multiple VMs with the same client payload. Selected DVD-Store (LAMP) scalability is mixed into here too and I wonder what type of test would you recommend to receive cleaner results? Regards, Alecattachment: kvm-vcpu-graph.png
Re: vCPU scalability for linux VMs
On 05/05/2010 04:45 AM, Alec Istomin wrote: Gentlemen, Reaching out with a non-development question, sorry if it's not appropriate here. I'm looking for a way to improve Linux SMP VMs performance under KVM. My preliminary results show that single vCPU Linux VMs perform up to 10 times better than 4vCPU Linux VMs (consolidated performance of 8 VMs on 8 core pre-Nehalem server). I suspect that I'm missing something major and look for any means that can help improve SMP VMs performance. So you have a total of 32 vcpus on 8 cores? This is known to be problematic. You may see some improvement by enabling hyperthreading. There is ongoing work to improve this. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: vCPU scalability for linux VMs
On Wednesday, May 5, 2010 at 04:43:32 -0400, Avi Kivity wrote: So you have a total of 32 vcpus on 8 cores? This is known to be problematic. You may see some improvement by enabling hyperthreading. exactly, 32 vCPUs on 8 core hardware that doesn't support hyperthreading (Clovertown E5335) There is ongoing work to improve this. If interested - let me know when is it going to be a good time/build to do the regression on this. -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: vCPU scalability for linux VMs
On Wednesday, May 5, 2010 at 13:27:39 -0400, Srivatsa Vaddagiri wrote: My preliminary results show that single vCPU Linux VMs perform up to 10 times better than 4vCPU Linux VMs (consolidated performance of 8 VMs on 8 core pre-Nehalem server). I suspect that I'm missing something major and look for any means that can help improve SMP VMs performance. Could you provide more details of what workload was used to compare this performance? It's Dell's DVD-Store LAMP stack test suite with Medium database (about 1 GB MySQL data) . 8x 2Gb VMs (on 16GB RAM host) with different vCPU configuration simultaneously loaded by external web clients. Regards, Alec -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: vCPU scalability for linux VMs
On Wed, May 05, 2010 at 12:31:11PM -0700, Alec Istomin wrote: On Wednesday, May 5, 2010 at 13:27:39 -0400, Srivatsa Vaddagiri wrote: My preliminary results show that single vCPU Linux VMs perform up to 10 times better than 4vCPU Linux VMs (consolidated performance of 8 VMs on 8 core pre-Nehalem server). I suspect that I'm missing something major and look for any means that can help improve SMP VMs performance. Could you provide more details of what workload was used to compare this performance? It's Dell's DVD-Store LAMP stack test suite with Medium database (about 1 GB MySQL data) . 8x 2Gb VMs (on 16GB RAM host) with different vCPU configuration simultaneously loaded by external web clients. Ok ..Do you have any more data on how the vCPU scalability looks like (how the throughput scales with increasing vCPUs)? - vatsa -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
vCPU scalability for linux VMs
Gentlemen,
Reaching out with a non-development question, sorry if it's not
appropriate here.
I'm looking for a way to improve Linux SMP VMs performance under KVM.
My preliminary results show that single vCPU Linux VMs perform up to 10
times better than 4vCPU Linux VMs (consolidated performance of 8 VMs on
8 core pre-Nehalem server). I suspect that I'm missing something major
and look for any means that can help improve SMP VMs performance.
VMs are started using:
qemu-kvm -m $ram -smp $cpus -name $name -drive
file=${newimg},boot=on,cache=writethrough -net
nic,macaddr=$mac,vlan=0,model=virtio -net
tap,script=/kvm/qemu-ifup,vlan=0,ifname=kvmnet$i -parallel none -usb -k en-us
-monitor pty -serial pty -nographic -daemonize -snapshot
KVM Host Environment (redhat 5 based):
# uname -r
2.6.18-194.el5
# rpm -qa|grep kvm
kvm-83-164.el5
kvm-tools-83-164.el5
kmod-kvm-83-164.el5
kvm-qemu-img-83-164.el5
Thank you,
Alec
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