Fix arc after kmem/kernel_arena merge
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Authored by jeff on Dec 14 2017, 9:37 PM.

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Reviewers

mav
avg
delphij
markj
scottl
allanjude

Commits

rS327485: Fix arc after r326347 broke various memory limit queries. Use UMA features

Summary

kernel_arena doesn't have the same initial size constraint as kmem did. This broke some of the arena logic in arc. Setting a limit on kernel_arena would produce other undesirable results and complications. Instead, I opted to use the uma limit feature directly. This required some FreeBSD specific ifdefs.

Test Plan

pho reports it is stable and no longer has a perf regression relatively to pre change.

Diff Detail

Repository

rS FreeBSD src repository - subversion

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Event Timeline

jeff created this revision.Dec 14 2017, 9:37 PM

Herald added a subscriber: imp. · View Herald TranscriptDec 14 2017, 9:37 PM

sbruno added a reviewer: allanjude.Dec 16 2017, 11:37 PM

markj accepted this revision.Dec 17 2017, 8:06 PM

This revision is now accepted and ready to land.Dec 17 2017, 8:06 PM

avg added inline comments.Dec 20 2017, 6:03 PM

cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
4293 ↗	(On Diff #36614)	I'd suggest not adding this new `ifdef` and instead moving `zio_area` definition to be alongside `heap_arena` in `sys/cddl/compat/opensolaris/sys/kmem.h`. If I correctly understand, now it will always be NULL on FreeBSD.
4337 ↗	(On Diff #36614)	This is FreeBSD-specific code. It's not present upstream at all. It was added by @mav in rS281109 and then transformed to the current shape when a big ZFS change was imported in rS286625. So, if we really think that that kind of check is not needed any longer in ARC, then this block and all traces of `FMR_ZIO_FRAG` can just be removed.