Skip SWAPBLK_NONEs with swap_pager_find_least() in swap_pager_copy().
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Authored by ota_j.email.ne.jp on Nov 6 2019, 5:36 AM.

Details

Reviewers

kib
dougm
alc

Summary

About 85% to 90% of them are SWAPBLK_NONE based on my experiments.
This will improve searching swblks by a factor of 2.5 to 10 by skipping
despite the cost of double lookups for non-SWAPBLK_NONE ones.

Test Plan

Regression after tapping into swap space.
I use 'make buildworld -j <high#>' to case page in/out.
I have test/experimental code with rate printf.

Diff Detail

Repository

rS FreeBSD src repository - subversion

Lint

Lint Passed

Unit

No Test Coverage

Build Status

Buildable 27416
Build 25660: arc lint + arc unit

Event Timeline

ota_j.email.ne.jp created this revision.Nov 6 2019, 5:36 AM

Herald added a subscriber: imp. · View Herald TranscriptNov 6 2019, 5:36 AM

Harbormaster completed remote builds in B27369: Diff 63991.Nov 6 2019, 5:36 AM

dougm mentioned this in D22280: exploit sparsity in swap_pager_copy.Nov 8 2019, 7:42 AM

Created swp_pager_meta_find_least private API to find and delete in a single
operation. swap_pager_find_least calls it for look up.

With this approach, we don't have any penalty for worst cases unlike the
first revision while expected performance gain doubled - 5 ~ 20 times faster
lookups.

Harbormaster completed remote builds in B27410: Diff 64098.Nov 9 2019, 3:44 AM

Fixed spaces/style.

I need to test this 2nd version, more.

Harbormaster completed remote builds in B27411: Diff 64099.Nov 9 2019, 3:49 AM

Correct swblk index and exclude swp_pager_swblk_free_empty() changes.

Harbormaster completed remote builds in B27416: Diff 64115.Nov 9 2019, 6:38 PM

D22280 has been committed.