Retbleed fix slugs Linux VM performance by up to 70 percent (UPDATED)
VMware engineers have tested the Linux kernel's fix for the Retbleed speculative execution bug, and report it can impact compute performance by a whopping 70 percent.
In a post to the Linux Kernel Mailing List titled "Performance Regression in Linux Kernel 5.19", VMware performance engineering staffer Manikandan Jagatheesan reports the virtualization giant's internal testing found that running Linux VMs on the ESXi hypervisor using version 5.19 of the Linux kernel saw compute performance dip by up to 70 percent when using single vCPU, networking fall by 30 percent and storage performance dip by up to 13 percent.
Jagatheesan said VMware's testers turned off the Retbleed remediation in version 5.19 of the kernel and ESXi performance returned to levels experienced under version 5.18.
Also: AMD readies additional RDNA 3 Code, GPU Reset Mode created for Radeon RX 6000 Series in Linux 6.1
UPDATE
Another site covers this today.
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The latest Linux kernel update could play havoc with your VMs | TechRadar
Computing performance for Linux VMs running the latest kernel update could have seen a decrease of up to 70%, new figures have found.
Recent research by VMWare performance engineering staffer Manikandan Jagatheesan found running virtual machines with the Linux distro on the ESXi hypervisor, using the latest kernel update version 5.19, could see computing power reduce by more than two-thirds when using a single vCPU.
Further ripple effects were also found in networking, with a loss of almost one-third, and storage performance, which saw up to a decrease of around one in ten.
Now the Micosofters write about it.
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VMware: 70% drop in Linux ESXi VM performance with Retbleed fixes
VMware is warning that ESXi VMs running on Linux kernel 5.19 can have up to a 70% performance drop when Retbleed mitigations are enabled compared to the Linux kernel 5.18 release.
More specifically, the VMware performance team noticed regressions on ESXi virtual machines of up to 70% in computing, 30% in networking, and 13% in storage.
FUD parade from Microsoft-connected site:
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Retbleed Security Fix Makes Linux go 70% Slower [Ed: Anti-Linux site spreads anti-Linux propaganda. This is about VMware, not Linux.]
The Linux kernel workaround for the ‘Retbleed’ vulnerability is causing a huge slowdown in tests. Performance runs of VMware guests show results up to 70% worse on slightly old hardware.
In a way, this was to be expected: When your workaround to a bug in a performance booster is to neuter the performance booster, you’d kinda expect the performance not to be so … boosted? Anyway, it’s hugely worrying for owners of older cloud server fleets.