kqueue: do not buffer the whole knote report when sizing it
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Authored by guest-seuros on Wed, Jul 29, 5:07 PM.

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adrian
imp
olce
markj

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rGff97443beef6: kqueue: do not buffer the whole knote report when sizing it

Summary

kern_proc_kqueues_out() reported into an intermediate sbuf and copied the
result into the caller's.

A process that had leaked 468k kqueue descriptors wired 757 MB of M_SBUF
while dumping core, over roughly 9M reallocations, then copied the whole
thing again.

PR 296835: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=296835

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rG FreeBSD src repository

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Tests Not Applicable

Event Timeline

guest-seuros created this revision.Wed, Jul 29, 5:07 PM

Herald added a subscriber: olce. · View Herald TranscriptWed, Jul 29, 5:07 PM

guest-seuros requested review of this revision.Wed, Jul 29, 5:07 PM

Harbormaster completed remote builds in B75269: Diff 183043.Wed, Jul 29, 5:07 PM

guest-seuros added a reviewer: olce.Wed, Jul 29, 5:08 PM

This is also bugzilla PR 296835: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=296835, please include that in the commit log message.

With the change we avoid the reallocations, but we're still potentially allocating a giant buffer when actually writing out the note, no? I don't really understand why kern_proc_kqueues_out() doesn't just use the caller-supplied sbuf.

This revision is now accepted and ready to land.Fri, Jul 31, 2:12 PM

rebase

This revision now requires review to proceed.Fri, Jul 31, 3:45 PM

Harbormaster completed remote builds in B75322: Diff 183168.Fri, Jul 31, 3:45 PM

adrian accepted this revision.Fri, Jul 31, 3:45 PM

This revision is now accepted and ready to land.Fri, Jul 31, 3:45 PM

guest-seuros edited the summary of this revision. (Show Details)Fri, Jul 31, 3:46 PM

Closed by commit rGff97443beef6: kqueue: do not buffer the whole knote report when sizing it (authored by guest-seuros, committed by adrian). · Explain WhyFri, Jul 31, 3:55 PM

This revision was automatically updated to reflect the committed changes.

adrian added a commit: rGff97443beef6: kqueue: do not buffer the whole knote report when sizing it.