From: "kosaki (Motohiro KOSAKI)" <kosaki.motohiro@...>
Date: 2012-12-03T12:29:17+09:00
Subject: [ruby-core:50503] [ruby-trunk - Bug #7500] Improve GC profiler timings on linux


Issue #7500 has been updated by kosaki (Motohiro KOSAKI).


And, if i understand the kernel source correctly, getrusage() and get_time(CLOCK_PROCESS_CPUTIME_ID) use the same clock source. So, I doubt this patch improve time accuracy.

Do anyone have a test result?
----------------------------------------
Bug #7500: Improve GC profiler timings on linux
https://bugs.ruby-lang.org/issues/7500#change-34342

Author: tmm1 (Aman Gupta)
Status: Open
Priority: Normal
Assignee: authorNari (Narihiro Nakamura)
Category: core
Target version: 2.0.0
ruby -v: ruby 2.0.0dev (2012-12-03 trunk 38149) [x86_64-darwin12.2.0]


On linux kernels, getrusage()'s precision depends on the value of HZ when the kernel was compiled. By default, HZ=250 provides a 4ms granularity.

This patch uses clock_gettime() with CLOCK_PROCESS_CPUTIME_ID when available, which provides a 1ns precision on linux.


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