Re: Request to backport commit f9cdeb58a9cf ("perf evlist: Avoid frequency mode for the dummy event") to stable versions of Linux kernel

On Wed, Nov 01, 2023 at 12:10:55PM -0700, Mingwei Zhang wrote:

Hi Greg,

Apology for any inconvenience. This is info and justification for patch.

Commit-id: f9cdeb58a9cf46c09b56f5f661ea8da24b6458c3 Subject: perf evlist: Avoid frequency mode for the dummy event

Justification:

This patch fixes a critical performance issue at perf-tool level for anything running PMU in a virtualized environment. Majority of the justification is within the commit message. The only thing I would like to add is that this patch could save up to 50% of the vCPU time when running perf in sampling mode with a large number of events in the VM.

Queued up, thanks!