From: Venkatesh Srinivas <me@endeavour.zapto.org>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] _xinc vs ainc
Date: Sat, 7 May 2011 22:44:34 -0400 [thread overview]
Message-ID: <BANLkTimu7W5+y4BwZzrUr-+_jkqsLRi+NA@mail.gmail.com> (raw)
In-Reply-To: <20110508012440.923D3B827@mail.bitblocks.com>
On Sat, May 7, 2011 at 9:24 PM, Bakul Shah <bakul@bitblocks.com> wrote:
> On Sat, 07 May 2011 20:25:25 EDT erik quanstrom <quanstro@quanstro.net> wrote:
>> > > the difference, and my main point is that the loop in ainc means
>> > > that it is not a wait-free algorithm. this is not only sub optimal,
>> > > but also could lead to incorrect behavior.
>> >
>> > I think a more likely possibility for the change is to have a
>> > *copy* of what was incremented. lock incl 0(ax) won't tell you
>> > what the value was when it was incremented.
>>
>> you can read the code. that value is not used by the thread library.
>
> If you want to use the value being atomically incremented,
> there is no more efficient way on x86. May not be used now but
> may be it can be used to make some synchronization primitive
> more efficient?
XADD
-- vs
next prev parent reply other threads:[~2011-05-08 2:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-07 13:05 erik quanstrom
2011-05-07 19:33 ` Bakul Shah
2011-05-07 22:47 ` erik quanstrom
2011-05-07 23:10 ` Bakul Shah
2011-05-08 0:25 ` erik quanstrom
2011-05-08 1:24 ` Bakul Shah
2011-05-08 2:44 ` Venkatesh Srinivas [this message]
2011-05-08 6:00 ` ron minnich
2011-05-08 13:14 ` erik quanstrom
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