QEMU/KVM running slow after kernel update

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EBAL
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QEMU/KVM running slow after kernel update

Post by EBAL » Tue Oct 16, 2018 4:48 pm

Hi, I'm running LM 18.3 on the host with the latest version of QEMU/KVM (via LM Update Manager). I have a number of LM 18.3 guests. The guests that were updated to the latest kernels 4.15.0-30 (and up) are performing very slow both on network and disk operation. The other guests still on an older kernel (4.10.x) have been running normally responsive.

I also installed LM 19 on another partition on same disk, booted it, installed QEMU/KVM and loaded the 18.3 guests with updated kernels - same slow performance.

Is anyone having similar isues? Is there a reason why updating the guests to the latest kernels is causing the slowdown?

Thanks,
EB

powerhouse
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Re: QEMU/KVM running slow after kernel update

Post by powerhouse » Mon Oct 29, 2018 7:26 am

I'm not sure, but perhaps the firmware updates for Spectre and Meltdown get in the way? I had slow 2D performance in my Windows VM when installing the firmware updates on the Windows VM.

I posted a bug report here: https://bugs.launchpad.net/qemu/+bug/1788665
Asus Sabertooth X79, i7 3930K CPU, 8x4GB Kingston DDR3, Noctua NH-D14 CPU cooler, GTX 970 + Quadro 2000 GPU, Asus Xonar Essence STX, Sandisk 120GB + Samsung EVO 860 1TB SSD + 4 HDD, Corsair 500R, SeaSonic 660W Gold X PS https://heiko-sieger.info

powerhouse
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Re: QEMU/KVM running slow after kernel update

Post by powerhouse » Mon Oct 29, 2018 7:53 am

Also note there have been some kernel updates lately. Make sure to update your kernel and check again.
Asus Sabertooth X79, i7 3930K CPU, 8x4GB Kingston DDR3, Noctua NH-D14 CPU cooler, GTX 970 + Quadro 2000 GPU, Asus Xonar Essence STX, Sandisk 120GB + Samsung EVO 860 1TB SSD + 4 HDD, Corsair 500R, SeaSonic 660W Gold X PS https://heiko-sieger.info

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