From: normalperson@...
Date: 2014-09-19T17:58:51+00:00
Subject: [ruby-core:65127] [ruby-trunk - Feature #10256] [PATCH] reduce rb_call_info_t 96 => 88 bytes on 64-bit

Issue #10256 has been updated by Eric Wong.

File 0001-make-rb_method_definition_t-smaller-via-rb_method_cf.patch added

Similar patch for rb_method_definition_t, tested on a different system due to
power outages.

Not much change, but minor improvements probably due to better locality
(method definitions are the same size as method entries, now).
http://80x24.org/bmlog-20140919-090128.6921

rb_method_definition_t is now 32 bytes (from 64) on a 64-bit system and
may be cache-aligned in the future to occupy half a 64-byte cache line.

Saves around 20K of allocations at startup with "valgrind ruby -e exit"
before:
  total heap usage: 49,445 allocs, 20,027 frees, 8,492,836 bytes allocated
after:
  total heap usage: 49,445 allocs, 20,040 frees, 8,472,372 bytes allocated


----------------------------------------
Feature #10256: [PATCH] reduce rb_call_info_t 96 => 88 bytes on 64-bit
https://bugs.ruby-lang.org/issues/10256#change-48978

* Author: Eric Wong
* Status: Open
* Priority: Normal
* Assignee: Koichi Sasada
* Category: core
* Target version: current: 2.2.0
----------------------------------------
Instead of using an 8-byte function pointer, use a small index
(may be <=1 byte, but currently 2 bytes for alignment) as array offset
and pack it next to flags (where only 9 bits are used).

Unfortunately, we cannot rely on C99, yet, so maintenance might be
a little uglier (but I think our test suite is good enough to cover).

Every word saved on rb_call_info_t seems to result in over 50K in startup
savings ("valgrind ruby -e exit").

before:
  total heap usage: 49,111 allocs, 19,776 frees, 8,444,054 bytes allocated
after:
  total heap usage: 49,057 allocs, 19,721 frees, 8,390,916 bytes allocated

Performance does not seem bad on Xeon E3-1230 v3 (8MB cache),
(minor +/- across the board):
http://80x24.org/bmlog-20140918-035740.9493


---Files--------------------------------
0001-rb_call_info_t-reduce-from-96-88-bytes-on-64-bit.patch (10.5 KB)
0001-make-rb_method_definition_t-smaller-via-rb_method_cf.patch (5.4 KB)


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