RFR: 8328307: GenShen: Re-enable old-has-grown trigger for old-generation GC

[William Kemper]

On Mon, 18 Mar 2024 13:32:16 GMT, Kelvin Nilsen <kdnilsen at openjdk.org> wrote:

> Enable old-gen growth triggers, which were inadvertantly disabled.  This passes the internal regression pipeline tests.
> 
> As would be expected, we see an increase in mixed-evacuation triggers.  We also see significant improvement on certain extremem workloads due to improved clearing of old-gen.
> 
> 
>    Control: shenandoah-x86-template
> Experiment: enable-old-growth-triggers-gh-x86
> 
>                           Most impacted benchmarks |                              Most impacted metrics
> -------------------------------------------------------------------------------------------------------
>                            Genshen/extremem-phased |                             trigger_expedite_mixed
>                 Genshen/specjbb2015_weak_ref_patch |                                    trigger_failure
>                                Genshen/specjbb2015 |                               context_switch_count
>                     Genshen/hyperalloc_a3072_o4096 |                                     sla_25000_jops
>                             Shenandoah/specjbb2015 |                                      trigger_learn
> 
> 
>                                 Only in experiment |                                    Only in control
> -------------------------------------------------------------------------------------------------------
>      hyperalloc_a2048_o2048/trigger_expedite_mixed |                   compress/concurrent_thread_roots
>      hyperalloc_a2048_o4096/trigger_expedite_mixed |                        crypto.rsa/ctr_thread_roots
>      hyperalloc_a3072_o2048/trigger_expedite_mixed |                               crypto.rsa/ctr_total
>      hyperalloc_a3072_o4096/trigger_expedite_mixed |               extremem-large-31g/trigger_expansion
>               extremem-large-31g/trigger_overgrown |                  extremem-phased/trigger_expansion
> 
> Genshen
> -------------------------------------------------------------------------------------------------------
> +685.00% specjbb2015_weak_ref_patch/trigger_expedite_mixed p=0.00002
>   Control:      2.500   (+/-  0.68  )         30
>   Test:        19.625   (+/-  4.79  )         10
> 
> +561.90% specjbb2015/trigger_expedite_mixed p=0.00001
>   Control:      2.625   (+/-  0.92  )         30
>   Test:        17.375   (+/-  3.89  )         10
> 
> +225.42% extremem-phased/trigger_expedite_mixed p=0.00000
>   Control:      9.833   (+/-  3.48  )         30
>   Test:        32.000   (+/-  2.58  )         10
> 
> +63.84% hyperalloc_a3072_o4096/evacuation p=0.02662
>   Control:     37....

test/hotspot/jtreg/gc/shenandoah/generational/TestOldGrowthTriggers.java line 42:

> 40: public class TestOldGrowthTriggers {
> 41: 
> 42:   public static void do_old_allocations() {

Nit, but Java convention is usually camel case: `doOldAllocations` or `makeOldAllocations` if the `oO` looks weird to you ;)

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PR Review Comment: https://git.openjdk.org/shenandoah/pull/409#discussion_r1528941440