| Message ID | 20231003122251.3325435-1-adhemerval.zanella@linaro.org |
|---|---|
| Headers | show |
| Series | Use introsort for qsort | expand |
On Tue, Oct 3, 2023 at 5:22 AM Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote: > > The motivation for using introsort is to make it fully AS-safe and > AC-Safe, with a limited stack size requirement, to remove the use of > malloc (which is troublesome since it seems some programs do longjmp > from the callback comparison program), and keep worst-case scenario > bounded to O(n*ln(n)) (instead of potentially quadradic as for the > quicksort). > > The implementation does not aim to be the state-of-the-art sort > algorithm, instead it uses used a well-understood introsort (used on > libstdc++, for instance) and leveraged the current quicksort > implementation along with a heapsort one from Linux kernel. > > Performance-wise, the introsort does fall short compared to the > mergesort [1]. I have not added a benchmark because I think this should > not be the focus of this patch. > > Changes from v7: > - Move __memswap to a static inline on its own header. > - Improve some comments. > > Changes from v6: > - Added internal __memswap symbol. > - Improved tst-qsort3 with a reference implementation and a new > duplicated input. > > Changes from v5: > - Rewrite heapsort to a custom implementation. > - Use may_alias attribute on swap optimization. > > Changes from v4 > - Use enum for swap function selection. > - Simplify is_aligned. > - Renamed insertsort. > > PS: this is a update for > https://sourceware.org/pipermail/libc-alpha/2023-October/151887.html > which should be ignored. > > Adhemerval Zanella (7): > string: Add internal memswap implementation > stdlib: Optimization qsort{_r} swap implementation > stdlib: Move insertion sort out qsort > stdlib: qsort: Move some macros to inline function > stdlib: Implement introsort for qsort (BZ 19305) > stdlib: Remove use of mergesort on qsort (BZ 21719) > stdlib: Add more qsort{_r} coverage > > include/stdlib.h | 2 - > manual/argp.texi | 2 +- > manual/locale.texi | 3 +- > manual/search.texi | 7 +- > stdlib/Makefile | 3 +- > stdlib/msort.c | 309 -------------------------------- > stdlib/qsort.c | 318 +++++++++++++++++++++++++-------- > stdlib/tst-qsort3.c | 366 ++++++++++++++++++++++++++++++++++++++ > string/Makefile | 12 ++ > string/test-memswap.c | 192 ++++++++++++++++++++ > sysdeps/generic/memswap.h | 41 +++++ > 11 files changed, 856 insertions(+), 399 deletions(-) > delete mode 100644 stdlib/msort.c > create mode 100644 stdlib/tst-qsort3.c > create mode 100644 string/test-memswap.c > create mode 100644 sysdeps/generic/memswap.h > > -- > 2.34.1 > Minus the nit about the memswap changes, this series looks good.
On 03/10/23 15:13, Noah Goldstein wrote: > On Tue, Oct 3, 2023 at 5:22 AM Adhemerval Zanella > <adhemerval.zanella@linaro.org> wrote: >> >> The motivation for using introsort is to make it fully AS-safe and >> AC-Safe, with a limited stack size requirement, to remove the use of >> malloc (which is troublesome since it seems some programs do longjmp >> from the callback comparison program), and keep worst-case scenario >> bounded to O(n*ln(n)) (instead of potentially quadradic as for the >> quicksort). >> >> The implementation does not aim to be the state-of-the-art sort >> algorithm, instead it uses used a well-understood introsort (used on >> libstdc++, for instance) and leveraged the current quicksort >> implementation along with a heapsort one from Linux kernel. >> >> Performance-wise, the introsort does fall short compared to the >> mergesort [1]. I have not added a benchmark because I think this should >> not be the focus of this patch. >> >> Changes from v7: >> - Move __memswap to a static inline on its own header. >> - Improve some comments. >> >> Changes from v6: >> - Added internal __memswap symbol. >> - Improved tst-qsort3 with a reference implementation and a new >> duplicated input. >> >> Changes from v5: >> - Rewrite heapsort to a custom implementation. >> - Use may_alias attribute on swap optimization. >> >> Changes from v4 >> - Use enum for swap function selection. >> - Simplify is_aligned. >> - Renamed insertsort. >> >> PS: this is a update for >> https://sourceware.org/pipermail/libc-alpha/2023-October/151887.html >> which should be ignored. >> >> Adhemerval Zanella (7): >> string: Add internal memswap implementation >> stdlib: Optimization qsort{_r} swap implementation >> stdlib: Move insertion sort out qsort >> stdlib: qsort: Move some macros to inline function >> stdlib: Implement introsort for qsort (BZ 19305) >> stdlib: Remove use of mergesort on qsort (BZ 21719) >> stdlib: Add more qsort{_r} coverage >> >> include/stdlib.h | 2 - >> manual/argp.texi | 2 +- >> manual/locale.texi | 3 +- >> manual/search.texi | 7 +- >> stdlib/Makefile | 3 +- >> stdlib/msort.c | 309 -------------------------------- >> stdlib/qsort.c | 318 +++++++++++++++++++++++++-------- >> stdlib/tst-qsort3.c | 366 ++++++++++++++++++++++++++++++++++++++ >> string/Makefile | 12 ++ >> string/test-memswap.c | 192 ++++++++++++++++++++ >> sysdeps/generic/memswap.h | 41 +++++ >> 11 files changed, 856 insertions(+), 399 deletions(-) >> delete mode 100644 stdlib/msort.c >> create mode 100644 stdlib/tst-qsort3.c >> create mode 100644 string/test-memswap.c >> create mode 100644 sysdeps/generic/memswap.h >> >> -- >> 2.34.1 >> > Minus the nit about the memswap changes, this series looks good. Thanks for the review, may I get reviewed-by ;) ?
On Fri, Oct 27, 2023 at 3:25 PM Adhemerval Zanella Netto <adhemerval.zanella@linaro.org> wrote: > > > > On 03/10/23 15:13, Noah Goldstein wrote: > > On Tue, Oct 3, 2023 at 5:22 AM Adhemerval Zanella > > <adhemerval.zanella@linaro.org> wrote: > >> > >> The motivation for using introsort is to make it fully AS-safe and > >> AC-Safe, with a limited stack size requirement, to remove the use of > >> malloc (which is troublesome since it seems some programs do longjmp > >> from the callback comparison program), and keep worst-case scenario > >> bounded to O(n*ln(n)) (instead of potentially quadradic as for the > >> quicksort). > >> > >> The implementation does not aim to be the state-of-the-art sort > >> algorithm, instead it uses used a well-understood introsort (used on > >> libstdc++, for instance) and leveraged the current quicksort > >> implementation along with a heapsort one from Linux kernel. > >> > >> Performance-wise, the introsort does fall short compared to the > >> mergesort [1]. I have not added a benchmark because I think this should > >> not be the focus of this patch. > >> > >> Changes from v7: > >> - Move __memswap to a static inline on its own header. > >> - Improve some comments. > >> > >> Changes from v6: > >> - Added internal __memswap symbol. > >> - Improved tst-qsort3 with a reference implementation and a new > >> duplicated input. > >> > >> Changes from v5: > >> - Rewrite heapsort to a custom implementation. > >> - Use may_alias attribute on swap optimization. > >> > >> Changes from v4 > >> - Use enum for swap function selection. > >> - Simplify is_aligned. > >> - Renamed insertsort. > >> > >> PS: this is a update for > >> https://sourceware.org/pipermail/libc-alpha/2023-October/151887.html > >> which should be ignored. > >> > >> Adhemerval Zanella (7): > >> string: Add internal memswap implementation > >> stdlib: Optimization qsort{_r} swap implementation > >> stdlib: Move insertion sort out qsort > >> stdlib: qsort: Move some macros to inline function > >> stdlib: Implement introsort for qsort (BZ 19305) > >> stdlib: Remove use of mergesort on qsort (BZ 21719) > >> stdlib: Add more qsort{_r} coverage > >> > >> include/stdlib.h | 2 - > >> manual/argp.texi | 2 +- > >> manual/locale.texi | 3 +- > >> manual/search.texi | 7 +- > >> stdlib/Makefile | 3 +- > >> stdlib/msort.c | 309 -------------------------------- > >> stdlib/qsort.c | 318 +++++++++++++++++++++++++-------- > >> stdlib/tst-qsort3.c | 366 ++++++++++++++++++++++++++++++++++++++ > >> string/Makefile | 12 ++ > >> string/test-memswap.c | 192 ++++++++++++++++++++ > >> sysdeps/generic/memswap.h | 41 +++++ > >> 11 files changed, 856 insertions(+), 399 deletions(-) > >> delete mode 100644 stdlib/msort.c > >> create mode 100644 stdlib/tst-qsort3.c > >> create mode 100644 string/test-memswap.c > >> create mode 100644 sysdeps/generic/memswap.h > >> > >> -- > >> 2.34.1 > >> > > Minus the nit about the memswap changes, this series looks good. > > Thanks for the review, may I get reviewed-by ;) ? LGTM with nit about memswap tests. Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
The motivation for using introsort is to make it fully AS-safe and AC-Safe, with a limited stack size requirement, to remove the use of malloc (which is troublesome since it seems some programs do longjmp from the callback comparison program), and keep worst-case scenario bounded to O(n*ln(n)) (instead of potentially quadradic as for the quicksort). The implementation does not aim to be the state-of-the-art sort algorithm, instead it uses used a well-understood introsort (used on libstdc++, for instance) and leveraged the current quicksort implementation along with a heapsort one from Linux kernel. Performance-wise, the introsort does fall short compared to the mergesort [1]. I have not added a benchmark because I think this should not be the focus of this patch. Changes from v7: - Move __memswap to a static inline on its own header. - Improve some comments. Changes from v6: - Added internal __memswap symbol. - Improved tst-qsort3 with a reference implementation and a new duplicated input. Changes from v5: - Rewrite heapsort to a custom implementation. - Use may_alias attribute on swap optimization. Changes from v4 - Use enum for swap function selection. - Simplify is_aligned. - Renamed insertsort. PS: this is a update for https://sourceware.org/pipermail/libc-alpha/2023-October/151887.html which should be ignored. Adhemerval Zanella (7): string: Add internal memswap implementation stdlib: Optimization qsort{_r} swap implementation stdlib: Move insertion sort out qsort stdlib: qsort: Move some macros to inline function stdlib: Implement introsort for qsort (BZ 19305) stdlib: Remove use of mergesort on qsort (BZ 21719) stdlib: Add more qsort{_r} coverage include/stdlib.h | 2 - manual/argp.texi | 2 +- manual/locale.texi | 3 +- manual/search.texi | 7 +- stdlib/Makefile | 3 +- stdlib/msort.c | 309 -------------------------------- stdlib/qsort.c | 318 +++++++++++++++++++++++++-------- stdlib/tst-qsort3.c | 366 ++++++++++++++++++++++++++++++++++++++ string/Makefile | 12 ++ string/test-memswap.c | 192 ++++++++++++++++++++ sysdeps/generic/memswap.h | 41 +++++ 11 files changed, 856 insertions(+), 399 deletions(-) delete mode 100644 stdlib/msort.c create mode 100644 stdlib/tst-qsort3.c create mode 100644 string/test-memswap.c create mode 100644 sysdeps/generic/memswap.h