Security News > 2022 > September > Retbleed slugs VM performance by up to 70 percent in kernel 5.19

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.

Because speculative execution exists to speed processing, it is no surprise that disabling it impacts performance.

A 70 percent decrease in computing performance will have a major impact on application performance that could lead to unacceptable delays for some business processes.

Do they take the performance hit, or do they decide that Retbleed, like its predecessors, is not easy to exploit and wear the risk of running without mitigation?

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https://go.theregister.com/feed/www.theregister.com/2022/09/12/retbleed_slugs_vm_performance_by/