From: Eric Wong <normalperson@yhbt.net>
To: Ruby developers <ruby-core@ruby-lang.org>
Subject: [ruby-core:61509] Re: [REJECT?] xmalloc/xfree: reduce atomic ops w/ thread-locals
Date: Sat, 15 Mar 2014 08:34:51 +0000 [thread overview]
Message-ID: <20140315083451.GA24736@dcvr.yhbt.net> (raw)
In-Reply-To: <5323FE11.3000908@atdot.net>
SASADA Koichi <ko1@atdot.net> wrote:
> (2014/03/14 2:12), Eric Wong wrote:
> > How about only using thread local and remove the process-wide globals?
>
> I doubt
>
> > Underflow from race conditions might cause too many GC runs.
>
> Let the counter(s) change addition only.
>
> separate then into:
> malloc_increase (increase only)
> free_increase (increase only)
>
> and use like that:
> if (malloc_incraese > free_increase &&
> malloc_incraese - free_increase > malloc_limit) {
> do_gc();
> }
>
> There are no underflow.
>
> In fact, I started this strategy just before releasing 2.1. However,
> "free_increase" is bigger than malloc_increase. Maybe this is someone's
> bug (for example, xfree for a malloced block) or my misunderstanding.
That probably works since it's a fuzzy hint counter anyways.
You may have hit xcalloc having no increase:
http://bogomips.org/ruby.git/patch?id=08fc03c25615
(maybe malloc_usable_size is broken on some systems w/ calloc ...)
> >> > # basically, GVL protects multi-threads parallel update of such values.
> >> > # this atomic operations only for call_without_gvl().
> >> > # so it is minor case.
> > Right. I am looking into using GVL less :)
> > For example, much of sweep phase may be done without GVL.
>
> I see. It is problem.
>
> # But parallel sweep on my exepriment doesn't show impressive speedup.
:< Were there also regressions?
I wonder if the speedup would be bigger if we use an allocator with
good MT scalability.
> BTW,
>
> > + rb_thread_t *th = ruby_thread_from_native();
>
> `th' can be NULL because no Ruby threads can call this code.
Did you mean: gsub(/no Ruby/, "non-Ruby") ?
I should put a FATAL exit there (but not much different than crashing).
next prev parent reply other threads:[~2014-03-15 8:38 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-12 0:06 [ruby-core:61424] [REJECT?] xmalloc/xfree: reduce atomic ops w/ thread-locals Eric Wong
2014-03-12 0:09 ` [ruby-core:61425] " Charlie Somerville
2014-03-12 1:07 ` [ruby-core:61426] " Eric Wong
2014-03-13 13:29 ` [ruby-core:61466] " SASADA Koichi
2014-03-13 17:12 ` [ruby-core:61471] " Eric Wong
2014-03-14 6:20 ` [ruby-core:61488] " Eric Wong
2014-03-15 7:15 ` [ruby-core:61508] " SASADA Koichi
2014-03-15 8:34 ` Eric Wong [this message]
2014-03-15 9:27 ` [ruby-core:61510] " SASADA Koichi
2014-03-15 20:41 ` [ruby-core:61519] " Eric Wong
2014-03-20 4:23 ` [ruby-core:61604] " SASADA Koichi
2014-03-20 8:12 ` [ruby-core:61608] " SASADA Koichi
2014-03-20 8:13 ` [ruby-core:61609] " SASADA Koichi
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