vmem: disable debug.vmem_check by default
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Authored by mjg on Sep 2 2021, 9:51 AM.

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kib
markj
scottl

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rG6352bbf7be9b: vmem: disable debug.vmem_check by default

Summary

It has a prohibitive performance impact when running real workloads.

Note this only affects kernels with DIAGNOSTIC.

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rG FreeBSD src repository

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mjg requested review of this revision.Sep 2 2021, 9:51 AM

mjg created this revision.

mjg edited the summary of this revision. (Show Details)

As I understand, DIAGNOSTIC is exactly for these kinds of expensive debug checks, similar to vmmap_check for example. What's the purpose of running a real workload with DIAGNOSTIC configured?

The workload at hand is poudriere and the goal is to make sure the kernel survives with debug.

Disabling vmem_check makes it chug along with ~10% system time, while it was getting multisecond stalls otherwise. This check is just too expensive to run without being explicitly requested.

Ok, I don't think it is very useful anyway.

This revision is now accepted and ready to land.Sep 2 2021, 3:30 PM

scottl accepted this revision.Sep 2 2021, 5:31 PM

Closed by commit rG6352bbf7be9b: vmem: disable debug.vmem_check by default (authored by mjg). · Explain WhySep 2 2021, 6:29 PM

This revision was automatically updated to reflect the committed changes.

mjg added a commit: rG6352bbf7be9b: vmem: disable debug.vmem_check by default.