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From: headius@headius.com
To: ruby-core@ruby-lang.org
Subject: [ruby-core:72528] [Ruby trunk - Feature #11339] [PATCH] io.c: avoid kwarg parsing in C API
Date: Sun, 27 Dec 2015 23:00:14 +0000
Message-ID: <redmine.journal-55792.20151227230013.530a3398859e3d58@ruby-lang.org> (raw)
In-Reply-To: <redmine.issue-11339.20150707215946@ruby-lang.org>

Issue #11339 has been updated by Charles Nutter.


A suggestion for how to make kwarg-passing to C functions allocation-free: have a thread-local (or perhaps global, since CRuby doesn't run Ruby code in parallel) array you can populate with the key/value pairs coming out of the VM. Methods that want to receive opts directly can specify it through a new rb_define_method form, and the requirement is that they must process those keyword arguments before doing anything else, so that global store can be re-used.

That is just a quick and dirty way to do it, but it would eliminate the need for hacks like this and make kwarg passing to C functions nearly free, as it is from Ruby to Ruby.

----------------------------------------
Feature #11339: [PATCH] io.c: avoid kwarg parsing in C API
https://bugs.ruby-lang.org/issues/11339#change-55792

* Author: Eric Wong
* Status: Closed
* Priority: Normal
* Assignee: 
----------------------------------------
~~~
rb_scan_args and hash lookups for kwargs in the C API are clumsy and
slow.  Instead of improving the C API for performance, use Ruby
instead :)

Implement IO#read_nonblock and IO#write_nonblock in prelude.rb
to avoid argument parsing via rb_scan_args and hash lookups.

This speeds up IO#write_nonblock and IO#read_nonblock benchmarks
in both cases, including the original non-idiomatic case where
the `exception: false' hash is pre-allocated to avoid GC pressure.

Now, writing the kwargs in natural, idiomatic Ruby is fastest.
I've added the noex2 benchmark to show this.

target 0: a (ruby 2.3.0dev (2015-07-08 trunk 51190) [x86_64-linux]) at "a/ruby"
target 1: b (ruby 2.3.0dev (2015-07-08 nonblock-kwarg 51190) [x86_64-linux]) at "b/ruby"
-----------------------------------------------------------
raw data:

[["io_nonblock_noex",
  [[2.5436805468052626, 2.5724728293716908, 2.4915440678596497],
   [2.478000810369849, 2.4285155069082975, 2.462410459294915]]],
 ["io_nonblock_noex2",
  [[3.012514788657427, 3.034533655270934, 2.9972082190215588],
   [2.135501991957426, 2.146781364455819, 2.0429874528199434]]]]

Elapsed time: 30.348340944 (sec)
-----------------------------------------------------------
benchmark results:
minimum results in each 3 measurements.
Execution time (sec)
name    a       b
io_nonblock_noex        2.492   2.429
io_nonblock_noex2       2.997   2.043

Speedup ratio: compare with the result of `a' (greater is better)
name    b
io_nonblock_noex        1.026
io_nonblock_noex2       1.467

Note: I plan to followup commits for other *_nonblock methods
Eventually, I even wish to deprecate rb_scan_args :D

For what it's worth, I'm more excited about this change than usual
and hope to use prelude.rb more.
~~~


---Files--------------------------------
0001-io.c-avoid-kwarg-parsing-in-C-API.patch (6.88 KB)


-- 
https://bugs.ruby-lang.org/

  parent reply	other threads:[~2015-12-27 22:27 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <redmine.issue-11339.20150707215946@ruby-lang.org>
2015-07-07 21:59 ` [ruby-core:69892] [Ruby trunk - Feature #11339] [Open] " normalperson
2015-07-15 19:41   ` [ruby-core:69983] " Eric Wong
2015-07-16  3:46     ` [ruby-core:69990] " SASADA Koichi
2015-07-16  7:01       ` [ruby-core:69995] " Eric Wong
2015-07-16  9:17         ` [ruby-core:69999] " SASADA Koichi
2015-10-09 23:35           ` [ruby-core:71035] " Eric Wong
2015-11-10 22:27   ` [ruby-core:71435] " Eric Wong
2015-12-02  2:23   ` [ruby-core:71789] " Eric Wong
2015-11-11  5:20 ` [ruby-core:71439] [Ruby trunk - Feature #11339] " matz
2015-11-12  2:03   ` [ruby-core:71459] " Eric Wong
2015-11-12  9:53     ` [ruby-core:71462] " Eric Wong
2015-11-18  2:07     ` [ruby-core:71539] " Eric Wong
2015-11-13  4:18   ` [ruby-core:71473] " Eric Wong
2015-11-13  5:46     ` [ruby-core:71478] " SASADA Koichi
2015-11-13  7:03       ` [ruby-core:71479] " Eric Wong
2015-12-27 22:49 ` [ruby-core:72527] " headius
2015-12-27 23:00 ` headius [this message]
2015-12-27 23:40   ` [ruby-core:72529] " Eric Wong
2015-12-28  0:13 ` [ruby-core:72530] " headius
2015-12-28  1:12   ` [ruby-core:72532] " Eric Wong
2015-12-28  0:22 ` [ruby-core:72531] " headius
2015-12-28  1:50 ` [ruby-core:72535] " headius

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