On Sun May 8 02:01:57 EDT 2011, rminn...@gmail.com wrote:
> The type signature reveals all: ainc returns a long, and xinc is void.
>
> You really can't test the value of the long * after you call xinc
> because somebody else might have done an xinc after your xinc but
> before you test the value.
The type signature reveals all: ainc returns a long, and xinc is void.
You really can't test the value of the long * after you call xinc
because somebody else might have done an xinc after your xinc but
before you test the value.
I think, among others, floren and I needed ainc for devtrace years
On Sat, May 7, 2011 at 9:24 PM, Bakul Shah wrote:
> On Sat, 07 May 2011 20:25:25 EDT erik quanstrom
> 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 incorrec
On Sat, 07 May 2011 20:25:25 EDT erik quanstrom 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 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
On Sat, 07 May 2011 18:47:54 EDT erik quanstrom wrote:
> > Just guessing. May be the new code allows more concurrency? If the
> > value is not in the processor cache, will the old code block other
> > processors for much longer? The new code forces caching with the first
> > read so may be
> Just guessing. May be the new code allows more concurrency? If the
> value is not in the processor cache, will the old code block other
> processors for much longer? The new code forces caching with the first
> read so may be high likelyhood cmpxchg will finish faster. I haven't
> studied
On May 7, 2011, at 6:05 AM, erik quanstrom
wrote:
i'm confused by the recent change to the thread library.
the old code was simply to do a locked incl. the new code
does a locked exchange /within a loop/ until it's seen that
nobody else has updated the value at the same time, thus
insuring t
