[ruby-core:64416] [ruby-trunk - Bug #10009] IO operation is 10x slower in multi-thread environment

Issue #10009 has been updated by Eric Wong.


 [e-mail] wrote:
 > I doubt I can noticeably improve performance with futexes vs mutex/condvar.
 
 Totally not-speed-optimized futex-based lock/condvar implementation at
 
 	git://bogomips.org/ruby.git (futex branch)
 	http://bogomips.org/ruby.git/patch?id=ae93c50c8de
 
 I am not sure if my implementation is correct, but "make check" passes
 with both 8 cores and 1 core active (8-core Vishera).  I will probably
 write an independent (C-only) test for more parallelism and maybe steal
 some from glibc (I also plan on using this futex-based lock
 implementation outside of Ruby).
 
 Benchmarks don't seem to show much (if any) improvement, yet.  Speed
 improvement from reimplementing GVL around bare futex interface may be
 possible (w/o using separate condvar/mutex layer).
 
 On amd64 GNU/Linux, pthread_mutex_t is 40 bytes, but these futex-based
 locks only need 4 bytes.  Similarly, pthread_cond_t is 48 bytes, making
 rb_nativethread_cond_t 56 bytes with pthreads; this futex implementation
 currently requires only 16 bytes for a condvar.
 
 Size improvement may be noticeable for some apps with many Mutexes:
 the lock/cond reductions mean rb_mutex_struct is now 48 bytes instead
 of 128 bytes.

----------------------------------------
Bug #10009: IO operation is 10x slower in multi-thread environment
https://bugs.ruby-lang.org/issues/10009#change-48372

* Author: Alexandre Riveira
* Status: Open
* Priority: Urgent
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.1 x ruby 1.9.2 with taskset
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
I created this issue #9832 but not have io operation.
In the script attached I simulate IO operation in multi-thread environment.
For ruby 1.9.2 apply `taskset -c -p 2 #{Process.pid}` for regulates threads behavior.
The second Thread is a io operation

My results:

1) ruby 2.1.2
first 43500194
second 95
third 42184385

2) ruby-2.0.0-p451
first 38418401
second 95
third 37444470

3) 1.9.3-p545
first 121260313
second 50
third 44275164

4) 1.9.2-p320
first 31189901
second 897 <============
third 31190598

Regards


Alexandre Riveira


---Files--------------------------------
teste_thread_schedule_2.rb (1.05 KB)
teste_thread_schedule.py (953 Bytes)
teste_thread_schedule.rb (955 Bytes)
test_thread_sched_pipe.rb (1.01 KB)


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