RFR: 8324649: Shenandoah: refactor implementation of free set [v5]

[Kelvin Nilsen]

> Several objectives:
> 1. Reduce humongous allocation failures by segregating regular regions from humongous regions
> 2. Do not retire regions just because an allocation failed within the region if the memory remaining within the region is large enough to represent a LAB
> 3. Track range of empty regions in addition to range of available regions in order to expedite humongous allocations
> 4. Treat collector reserves as available for Mutator allocations after evacuation completes
> 5. Improve encapsulation so as to enable an OldCollector reserve for future integration of generational Shenandoah
> 
> On internal performance pipelines, this change shows:
> 
>  1. some Increase in page faults and rss_max with certain workloads, presumably because of "segregation" of humongous from regular regions.
>  2. An increase in System CPU time on certain benchmarks: sunflow (+165%), scimark.sparse.large (+50%), lusearch (+43%).  This system CPU time increase appears to correlate with increased page faults and/or rss.
>  3. An increase in trigger_failure for the hyperalloc_a2048_o4096 experiment (not yet understood)
>  4. 2-30x improvements on multiple metrics of the Extremem phased workload latencies (most likely resulting from fewer degenerated or full GCs)
> 
> Shenandoah
> -------------------------------------------------------------------------------------------------------
> +166.55% scimark.sparse.large/minor_page_fault_count p=0.00000
>   Control: 819938.875   (+/-5724.56  )         40
>   Test:    2185552.625   (+/-26378.64  )         20
> 
> +166.16% scimark.sparse.large/rss_max p=0.00000
>   Control: 3285226.375   (+/-22812.93  )         40
>   Test:    8743881.500   (+/-104906.69  )         20
> 
> +164.78% sunflow/cpu_system p=0.00000
>   Control:      1.280s  (+/-  0.10s )         40
>   Test:         3.390s  (+/-  0.13s )         20
> 
> +149.29% hyperalloc_a2048_o4096/trigger_failure p=0.00000
>   Control:      3.259   (+/-  1.46  )         33
>   Test:         8.125   (+/-  2.05  )         20
> 
> +143.75% pmd/major_page_fault_count p=0.03622
>   Control:      1.000   (+/-  0.00  )         40
>   Test:         2.438   (+/-  2.59  )         20
> 
> +80.22% lusearch/minor_page_fault_count p=0.00000
>   Control: 2043930.938   (+/-4777.14  )         40
>   Test:    3683477.625   (+/-5650.29  )         20
> 
> +50.50% scimark.sparse.small/minor_page_fault_count p=0.00000
>   Control: 697899.156   (+/-3457.82  )         40
>   Test:    1050363.812   (+/-175237.63  )         20
> 
> +49.97% scimark.sparse.small/rss_max p=0.00000
>   Control: 277075...

Kelvin Nilsen has updated the pull request incrementally with 10 additional commits since the last revision:

 - Change names of shrink_bounds_if_touched and expand_bounds_maybe
 - Add comments to describe _leftmosts and _rightmosts and _empty ranges
 - Change shrink_bounds_if_touched to shrink_range_if_boundary_modified
 - Change clear_internal() to make_all_regions_unavailable()
 - Remove mention of vestigial evac_expended in comment
 - Fix comment in allocate_single()
 - Clarify preconditions for allocate_single and allocate_contiguous
 - More consistent naming of partitions vs sets
 - Change ShenandoahSetsOfFreeRegions to ShenandoahRegionPartition
 - Replace ShenandoahFreeMemoryType with ShenandoahFreeSetRegionType

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/17561/files
  - new: https://git.openjdk.org/jdk/pull/17561/files/813ba6ef..7816f3a5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17561&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17561&range=03-04

  Stats: 334 lines in 3 files changed: 26 ins; 15 del; 293 mod
  Patch: https://git.openjdk.org/jdk/pull/17561.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17561/head:pull/17561

PR: https://git.openjdk.org/jdk/pull/17561