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Feature #10575

closed

[RFC] struct: avoid all O(n) behavior on access

Added by normalperson (Eric Wong) almost 10 years ago. Updated almost 10 years ago.

Status:
Closed
Target version:
[ruby-core:66729]

Description

This avoids O(n) on lookups with structs over 10 members.
This also avoids O(n) behavior on all assignments on Struct members.
Members 0..9 still use existing C methods to read in O(1) time

Benchmark results:

vm2_struct_big_aref_hi*	1.305
vm2_struct_big_aref_lo*	1.157
vm2_struct_big_aset*	3.306
vm2_struct_small_aref*	1.015
vm2_struct_small_aset*	3.273

Note: I chose use loading instructions from an array instead of writing
directly to linked-lists in compile.c for ease-of-maintainability. We
may move the method definitions to prelude.rb-like files in the future.

I have also tested this patch with the following patch to disable
the C ref_func methods and ensured the test suite and rubyspec works

--- a/struct.c
+++ b/struct.c
@@ -209,7 +209,7 @@ setup_struct(VALUE nstr, VALUE members)
	ID id = SYM2ID(ptr_members[i]);
	VALUE off = LONG2NUM(i);
 
-	if (i < N_REF_FUNC) {
+	if (0 && i < N_REF_FUNC) {
	    rb_define_method_id(nstr, id, ref_func[i], 0);
	}
	else {

Files

struct_iseq-v1-r48725.patch (10.8 KB) struct_iseq-v1-r48725.patch normalperson (Eric Wong), 12/06/2014 12:31 AM

Updated by nobu (Nobuyoshi Nakada) almost 10 years ago

  • Description updated (diff)

Looks fine.

Actions #2

Updated by Anonymous almost 10 years ago

  • Status changed from Open to Closed
  • % Done changed from 0 to 100

Applied in changeset r48748.


struct: avoid all O(n) behavior on access

This avoids O(n) on lookups with structs over 10 members.
This also avoids O(n) behavior on all assignments on Struct members.
Members 0..9 still use existing C methods to read in O(1) time

Benchmark results:

vm2_struct_big_aref_hi* 1.305
vm2_struct_big_aref_lo* 1.157
vm2_struct_big_aset* 3.306
vm2_struct_small_aref* 1.015
vm2_struct_small_aset* 3.273

Note: I chose use loading instructions from an array instead of writing
directly to linked-lists in compile.c for ease-of-maintainability. We
may move the method definitions to prelude.rb-like files in the future.

I have also tested this patch with the following patch to disable
the C ref_func methods and ensured the test suite and rubyspec works

--- a/struct.c
+++ b/struct.c
@@ -209,7 +209,7 @@ setup_struct(VALUE nstr, VALUE members)
	ID id = SYM2ID(ptr_members[i]);
	VALUE off = LONG2NUM(i);

-	if (i < N_REF_FUNC) {
+	if (0 && i < N_REF_FUNC) {
	    rb_define_method_id(nstr, id, ref_func[i], 0);
	}
	else {
  • iseq.c (rb_method_for_self_aref, rb_method_for_self_aset):
    new methods to generate bytecode for struct.c
    [Feature #10575]
  • struct.c (rb_struct_ref, rb_struct_set): remove
    (define_aref_method, define_aset_method): new functions
    (setup_struct): use new functions
  • test/ruby/test_struct.rb: add test for struct >10 members
  • benchmark/bm_vm2_struct_big_aref_hi.rb: new benchmark
  • benchmark/bm_vm2_struct_big_aref_lo.rb: ditto
  • benchmark/bm_vm2_struct_big_aset.rb: ditto
  • benchmark/bm_vm2_struct_small_aref.rb: ditto
  • benchmark/bm_vm2_struct_small_aset.rb: ditto

Updated by funny_falcon (Yura Sokolov) almost 10 years ago

Couple of other struct optimizations in #10585

Updated by ko1 (Koichi Sasada) almost 10 years ago

Sorry for late.

Benchmark results:

vm2_struct_big_aref_hi* 1.305
...

how to read? seconds? compared ratio with non-opt version?

Updated by normalperson (Eric Wong) almost 10 years ago

speedup ratio (from benchmark/driver.rb)

Updated by normalperson (Eric Wong) almost 10 years ago

wrote:

Couple of other struct optimizations in #10585

Thanks. Btw, can you reproduce the issue in [ruby-core:66762]? I
cannot reproduce it anymore on 32-bit x86, so I'm not sure if further
digging is required [ruby-core:66764]

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