pipe: Avoid unnecessary priv_check() calls in pipespace_new()
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Authored by markj on Thu, Feb 19, 5:01 PM.

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jhb
kib
olce

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rGfa77660a3ccb: pipe: Avoid unnecessary priv_check() calls in pipespace_new()

Summary

Running out of pipe map KVA is a rare case, so reorder checks
accordingly, presuming that calling priv_check() is more expensive than
the calculation. We might further consider precomputing
maxpipekva / 100 at boot time to avoid the division here.

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rG FreeBSD src repository

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Buildable 70785
Build 67668: arc lint + arc unit

Event Timeline

markj created this revision.Thu, Feb 19, 5:01 PM

Herald added a subscriber: imp. · View Herald TranscriptThu, Feb 19, 5:01 PM

markj requested review of this revision.Thu, Feb 19, 5:01 PM

markj added a parent revision: D55377: sysctl: Avoid calling priv_check() unnecessarily.

Harbormaster completed remote builds in B70785: Diff 172255.Thu, Feb 19, 5:01 PM

You could divide by 128 if this is so important.

Could you please explain the motivation for the changes?

This revision is now accepted and ready to land.Thu, Feb 19, 5:37 PM

In D55378#1266686, @kib wrote:

You could divide by 128 if this is so important.

Could you please explain the motivation for the changes?

I was looking at sources of frequent priv_check() calls from unprivileged processes, trying to see if any are avoidable. These calls might do some non-trivial work if MAC hooks are installed.

In D55378#1266700, @markj wrote:

In D55378#1266686, @kib wrote:

You could divide by 128 if this is so important.

Could you please explain the motivation for the changes?

I was looking at sources of frequent priv_check() calls from unprivileged processes, trying to see if any are avoidable. These calls might do some non-trivial work if MAC hooks are installed.