From: nobu@...
Date: 2014-03-03T00:46:40+00:00
Subject: [ruby-core:61238] [ruby-trunk - Bug #9262] global_method_cache should be configurable or grow automatically

Issue #9262 has been updated by Nobuyoshi Nakada.


Eric Wong wrote:
> nobu@ruby-lang.org wrote:
>  > Eric Wong wrote:
>  > >  It also replaces CPP #if with C if for readability.
>  > 
>  > I don't think it is needed.
>  
>  OK, does it that mean UNDEFINED_METHOD_ENTRY_P is unnecessary
>  with cache disabled?  Could just do this:
>  	http://80x24.org/gmc_disable.patch

I meant "replace CPP #if with C".


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Bug #9262: global_method_cache should be configurable or grow automatically
https://bugs.ruby-lang.org/issues/9262#change-45583

* Author: Aman Gupta
* Status: Open
* Priority: Normal
* Assignee: Koichi Sasada
* Category: 
* Target version: next minor
* ruby -v: -
* Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN
----------------------------------------
The global_method_cache is currently a fixed 2048 entries. This is not configurable, and can be inadequate for large applications with thousands of classes and methods.

In our app, increasing the size of the cache to 32768 entries reduced time spent in search_method and overall pressure on st_lookup:

before
      420  14.0% st_lookup
      182   6.1% vm_search_method (inline)

after
      265   9.5% st_lookup
      125   4.5% vm_search_method (inline)

It's possible the VM could grow global_method_cache automatically, using some heuristic based on the number of long-lived classes or method_entries that are defined.
However this would break the hashing in the current implementation.



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