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Skip SWAPBLK_NONEs with swap_pager_find_least() in swap_pager_copy().
AbandonedPublic

Authored by ota_j.email.ne.jp on Wed, Nov 6, 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
Lint
Lint OK
Unit
No Unit Test Coverage
Build Status
Buildable 27416
Build 25660: arc lint + arc unit

Event Timeline

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.

Fixed spaces/style.

I need to test this 2nd version, more.

Correct swblk index and exclude swp_pager_swblk_free_empty() changes.

ota_j.email.ne.jp abandoned this revision.Fri, Nov 15, 8:42 AM

D22280 has been committed.