On Fri, 15 Sep 2023 20:17:17 GMT, Paul Sandoz <psan...@openjdk.org> wrote:
>>> Alan, you mentioned that DualPivotQuicksort will need detailed review. Can >>> we go ahead and start reviewing? Laurent checked performance, JMH results >>> look fine. >> >> As before, I think the main question with this change is whether adding >> radix sort to the mix is worth the complexity and additional code to >> maintain. Also as we discussed in the previous PR, the additional memory >> needed for the radix sort may have an effect on other things that are going >> on concurrently. I know it has been updated to handle OOME but I think >> potential reviewers would need to be comfortable with that part. > >> > Alan, you mentioned that DualPivotQuicksort will need detailed review. Can >> > we go ahead and start reviewing? Laurent checked performance, JMH results >> > look fine. >> >> As before, I think the main question with this change is whether adding >> radix sort to the mix is worth the complexity and additional code to >> maintain. Also as we discussed in the previous PR, the additional memory >> needed for the radix sort may have an effect on other things that are going >> on concurrently. I know it has been updated to handle OOME but I think >> potential reviewers would need to be comfortable with that part. > > I too share concerns about the potential increased use of memory for sorting > ints/longs/floats/doubles. With modern SIMD hardware and data parallel > techniques we can apply quicksort much more efficiently. I think it is > important to determine to what extent this reduces the need for radix sort. > To determine that we would need to carefully measure against the AVX-512 > implementation (with ongoing improvements) with appropriately initialized > data to sort, and further measure against an AVX2 version. > Hi Paul (@PaulSandoz), Alan (@AlanBateman), Any update? Do you agree with > Radix sort in parallel case only? I think its definitely a better fit, but another aspect of my previous comment was wondering if we need a radix sort if the vectorized quicksort implementation is fast enough. IMO we need to compare performance results with the vectorized quick sort, and be aware of future enhancements to that. ------------- PR Comment: https://git.openjdk.org/jdk/pull/13568#issuecomment-1728082819
