Feature #11170: [PATCH] use ivar indices for generic ivars

• Status: Closed
• Assignee: -
• Target version: -

[normalperson (Eric Wong)]

• [PATCH 1/2] variable.c: extract common functions for generic ivar
  http://80x24.org/spew/m/4e9df8a150a121c894fe142bde5efc15d43e5e94.txt
• [PATCH 2/2] variable.c: use indices for generic ivars
  http://80x24.org/spew/m/aabb09c886a23ea496722b13f2b39da8606b8180.txt

This reduces memory overhead of ivars for common types such as
T_DATA the same way T_OBJECT does it.

For 9992 accepted clients on an OpenSSL server, this reduces RSS memory
from 77160K to 69248K on x86-64 with the attached ossl.rb script.
Connecting client process was reduced from 246312K to 230724K RSS.

OpenSSL 1.0.1e-2+deb7u16 on Debian 7

[normalperson (Eric Wong)]

• File ossl_11170.rb ossl_11170.rb added

Attached standalone test script, increase "ulimit -n" as necessary.

[ko1 (Koichi Sasada)]

+1.

T_CLASS/T_MODULE can use same technique, but it seems not so many use-cases.

[normalperson (Eric Wong)]

After the original patch, rb_generic_ivar_table() is much more expensive
but kept for compatibility reasons. I propose deprecating it, I'm not
sure if any 3rd party C-exts use it.

http://80x24.org/spew/m/[e-mail]

[PATCH 3/2] avoid compatibility table with generic ivars

This recovers and improves performance of Marshal.dump/load on
Time objects compared to when we implemented generic ivars
entirely using st_table.

This also recovers some performance on other generic ivar objects,
but does not bring bring Marshal.dump/load performance up to
previous speeds.

benchmark results:
minimum results in each 10 measurements.
Execution time (sec)
name trunk geniv after
marshal_dump_flo 0.343 0.334 0.335
marshal_dump_load_geniv 0.487 0.527 0.495
marshal_dump_load_time 1.262 1.401 1.257

Speedup ratio: compare with the result of `trunk' (greater is better)
name geniv after
marshal_dump_flo 1.026 1.023
marshal_dump_load_geniv 0.925 0.985
marshal_dump_load_time 0.901 1.004

• Status changed from Open to Closed

Applied in changeset r50678.

---

variable.c: use indices for generic ivars

This reduces memory overhead of ivars for common types such as
T_DATA the same way T_OBJECT does it.

For 9992 accepted clients on an OpenSSL server, this reduces
memory from 77160K to 69248K with the script in
https://bugs.ruby-lang.org/issues/11170

• variable.c (static int special_generic_ivar): move
  (rb_generic_ivar_table): rewrite for compatibility
  (gen_ivtbl_bytes): new function
  (generic_ivar_get): update to use ivar index
  (generic_ivar_update): ditto
  (generic_ivar_set): ditto
  (generic_ivar_defined): ditto
  (generic_ivar_remove): ditto
  (rb_mark_generic_ivar): ditto
  (givar_i): ditto
  (rb_free_generic_ivar): ditto
  (rb_mark_generic_ivar_tbl): ditto
  (rb_generic_ivar_memsize): ditto
  (rb_copy_generic_ivar): ditto
  (rb_ivar_set): ditto
  (rb_ivar_foreach): ditto
  (rb_ivar_count): ditto
  (givar_mark_i): remove
  (gen_ivtbl_mark): new function
  (gen_ivar_each): ditto
  (iv_index_tbl_extend): update for struct ivar_update
  (iv_index_tbl_newsize): ditto
  [ruby-core:69323] [Feature #11170]