From: Eric Wong <normalperson@yhbt.net>
To: Ruby developers <ruby-core@ruby-lang.org>
Subject: [ruby-core:68180] Re: [Ruby trunk - Bug #10867] [Feedback] An ATOMIC_GET operation should be written and used.
Date: Thu, 19 Feb 2015 04:38:30 +0000 [thread overview]
Message-ID: <20150219043829.GA3674@dcvr.yhbt.net> (raw)
In-Reply-To: <redmine.journal-51551.20150219031408.3caf1b60c274f831@ruby-lang.org>
nobu@ruby-lang.org wrote:
> Won't atomic operations using gcc's `__atomic`/`__sync` built-ins or other
> platform-provided functions make such barriers?
Yes, but we don't use these builtins for reading (rb_signal_buff_size, for
example)
For a CPU memory barrier, I've used a no-op "+ 0" to read a counter:
__sync_add_and_fetch(&counter, 0)
If only a compiler barrier is necessary, I prefer to avoid volatile types
and use something like an ACCESS_ONCE macro (similar to our RB_GC_GUARD)
to cast to volatile as-needed.
I really wish Ruby were GPL so it can rely on URCU for nice things :/
next prev parent reply other threads:[~2015-02-19 4:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <redmine.issue-10867.20150218180006@ruby-lang.org>
2015-02-18 18:00 ` [ruby-core:68173] [Ruby trunk - Bug #10867] [Open] An ATOMIC_GET operation should be written and used sstewartgallus00
2015-02-19 3:14 ` [ruby-core:68177] [Ruby trunk - Bug #10867] [Feedback] " nobu
2015-02-19 4:38 ` Eric Wong [this message]
2015-02-19 4:35 ` [ruby-core:68178] [Ruby trunk - Bug #10867] " nobu
2015-02-19 22:19 ` [ruby-core:68193] " kosaki.motohiro
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