On Thu, Dec 20, 2018 at 12:17 AM Chris M. Thomasson <cris...@charter.net> wrote:
>
> On Wednesday, December 19, 2018 at 2:02:31 AM UTC-8, Dmitry Vyukov wrote:
>>
>> On Wed, Dec 19, 2018 at 7:05 AM Chris M. Thomasson <cri...@charter.net>
>> wrote:
>> >
>> > On Monday, December 17, 2018 at 11:23:20 PM UTC-8, Chris M. Thomasson
>> > wrote:
>> >>
>> >> If interested, I can give more details. For now, here is the code in the
>> >> form of a Relacy Test Unit:
>>
>> Can you give a short executive summary? What are the
>> advantages/disadvantages/novelty?
>
>
> Very quick, sorry: Should have some more time tonight.
>
> A simple proxy with per-thread mutexes. Threads enter a protected region by
> taking their own lock, and leave it by releasing said lock. Very basic. When
> a thread wants to defer a node for deletion it pushes it onto a global
> lock-free stack via CAS. There is a reaper thread that flushes all of the
> nodes with XCHG, and keeps it on an internal list. The reaper thread loop
> then tries to acquire and release all of the per-thread locks. Once it has
> done this, it says quiescent state. It keeps nodes in a way that ensures at
> least two periods of this state have occurred before it actually calls delete
> and destroys memory. Since the reapers use a try_lock to detect a quiescent
> state, it can livelock in a reaper in the sense that it never gains a lock.
> However, Relacy should never detect the condition because of the limited
> iteration loop for workers wrt the test code itself. There is a work around.
> We can let a reaper fail for a little while before it actually ditches
> try_lock and just locks the per-thread quiescence lock. It would act just
> like an adaptive mutex, in a sense...
So the main advantage is simplicity and ability for mere mortals to
understand how it works :)
Should be especially advantageous in teaching since it does not
involve atomic operations.
> _______________
> fresh = new generation
> old = old generation
>
> // reaper loop
>
> fresh = gain new nodes
>
> if (quiescent)
> {
> dump = old;
> old = fresh;
> fresh = empty;
>
> dump.destroy(); // reclaim memory...
> }
> _______________
>
>
>>
>>
>>
>> >> https://pastebin.com/raw/FpnvTqvM
>> >> (raw link, no ads! :^)
>> >>
>> >> ___________________________
>> >>
>> >> [...]
>> >>
>> >> ___________________________
>> >>
>> >>
>> >>
>> >> Can anybody run it with Relacy? If not, I need to learn why: what
>> >> problems were encountered?
>>
>> Did you succeed with running it with Relacy? :)
>
>
> So far, so good. It passes 10000000 iterations. I am letting rl::sched_bound
> run for around 65 minutes now, no problems at iteration:
>
>
> 99% (129564672/129564673)
>
> 99% (129630208/129630209)
>
> 99% (129695744/129695745)
>
> 99% (129761280/129761281)
>
> 99% (129826816/129826817)
>
> 99% (129892352/129892353)
>
> 99% (129957888/129957889)
>
> 99% (130023424/130023425)
>
> [...]
>
>
>
> Also, need to get the latest version of Relacy. I am using version: 2.3.
>
>
> Does it bite the dust in the latest version? ;^o
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