It's a matter of intuition how much free lists improve TS performance,
I'm not so sure it's worth it either. But I do feel it's clear that,
if we are going to to use freelists, my implementation is strongly
preferable. Based on the preferability of clear, minimal interfaces
and lack of unnecessary complexity. We can sink into paralysis where
we are scared to clean up anything, and remain permanently scared
because we never clean up anything.
On Sun, Dec 9, 2018 at 2:33 PM Bryan Call <bc...@apache.org> wrote:
>
> I agree, there are other problems that would take priority over
> reimplementing the free list.
>
> -Bryan
>
>
>
> > On Dec 8, 2018, at 10:59 AM, Leif Hedstrom <zw...@apache.org> wrote:
> >
> >
> >
> >> On Dec 7, 2018, at 18:10, Walt Karas <wka...@oath.com.invalid> wrote:
> >>
> >> How does one migrate improper code properly?
> >
> > You get rid of it. I’d argue that what we have works fine, has worked fine
> > for years and your are replacing with something that we will replace
> > anyways.
> >
> > Focus on real problems IMO.
> >
> > — Leif
> >
> >
> >>> On Fri, Dec 7, 2018 at 5:54 PM Leif Hedstrom <zw...@apache.org> wrote:
> >>>
> >>>
> >>>
> >>>> On Dec 7, 2018, at 1:02 PM, Walt Karas <wka...@oath.com.INVALID> wrote:
> >>>>
> >>>> It's the same general idea as the current free lists, but with a
> >>>> better, cleaner implementation. If there are a lot of smaller dynamic
> >>>> objects with short lifetimes, it will reduce thread blocking on the
> >>>> heap mutex, block coalescing, and relatively complex changes to the
> >>>> data structure of free blocks.
> >>>
> >>>
> >>> I’m pretty meh on this proposal. If it’s not broken, don’t fix it. I
> >>> much rather hold off until someone is interested in doing real work on
> >>> migrating the freelist over to jemalloc properly.
> >>>
> >>> — leif
> >>>
> >>>>> On Fri, Dec 7, 2018 at 12:54 PM Leif Hedstrom <zw...@apache.org> wrote:
> >>>>>
> >>>>> What problem does solve? Does it make things faster?
> >>>>>
> >>>>> — Leif
> >>>>>
> >>>>>> On Dec 7, 2018, at 09:27, Walt Karas <wka...@oath.com.invalid> wrote:
> >>>>>>
> >>>>>> This doesn't conflict with those efforts, and is much easier to do.
> >>>>>>> On Thu, Dec 6, 2018 at 6:56 PM Leif Hedstrom <zw...@apache.org> wrote:
> >>>>>>>
> >>>>>>> I thought the efforts were to be focused on getting jemalloc
> >>>>>>> optimized with their concepts of arenas and NUMA affinity and thread
> >>>>>>> ware allocations?
> >>>>>>>
> >>>>>>> — Leif
> >>>>>>>
> >>>>>>>> On Dec 6, 2018, at 15:02, Walt Karas <wka...@oath.com.invalid> wrote:
> >>>>>>>>
> >>>>>>>> Would it be desirable for ATS to use this (cleaner) version of free
> >>>>>>>> lists?
> >>>>>>>>
> >>>>>>>> https://github.com/ywkaras/MiscRepo/blob/master/Dynamic_obj/example.cc
> >>>>>>>>
> >>>>>>>> https://github.com/ywkaras/MiscRepo/blob/master/Dynamic_obj/Dynamic_obj.h
> >>>>>>>>
> >>>>>>>> The advantage is faster allocation/deallocation for small objects
> >>>>>>>> with
> >>>>>>>> short lifetimes. The disadvantage is we could reach heap exhaustion
> >>>>>>>> more easily, as the free lists are reserving free memory for
> >>>>>>>> allocation of a particular size (and where the size is a constexpr).
> >>>>>>>>
> >>>>>>>> We would probably want to use conditional compilation for force
> >>>>>>>> Large_threshold to 0 for FSAN builds and maybe debug builds also.
> >>>>>>>
> >>>>>
> >>>
> >
>
