On Wed, Jul 28, 2021 at 7:00 PM Alexander Motin <m...@freebsd.org> wrote:
> The branch main has been updated by mav: > > URL: > https://cgit.FreeBSD.org/src/commit/?id=aefe0a8c32d370f2fdd0d0771eb59f8845beda17 > > commit aefe0a8c32d370f2fdd0d0771eb59f8845beda17 > Author: Alexander Motin <m...@freebsd.org> > AuthorDate: 2021-07-29 01:18:50 +0000 > Commit: Alexander Motin <m...@freebsd.org> > CommitDate: 2021-07-29 02:00:29 +0000 > > Refactor/optimize cpu_search_*(). > > Remove cpu_search_both(), unused for many years. Without it there is > less sense for the trick of compiling common cpu_search() into separate > cpu_search_lowest() and cpu_search_highest(), so split them completely, > making code more readable. While there, split iteration over children > groups and CPUs, complicating code for very small deduplication. > > Stop passing cpuset_t arguments by value and avoid some manipulations. > Since MAXCPU bump from 64 to 256, what was a single register turned > into 32-byte memory array, requiring memory allocation and accesses. > Splitting struct cpu_search into parameter and result parts allows to > even more reduce stack usage, since the first can be passed through > on recursion. > > Remove CPU_FFS() from the hot paths, precalculating first and last CPU > for each CPU group in advance during initialization. Again, it was > not a problem for 64 CPUs before, but for 256 FFS needs much more code. > > With these changes on 80-thread system doing ~260K uncached ZFS reads > per second I observe ~30% reduction of time spent in cpu_search_*(). Nice! I recall seeing contention here on other workloads on high core count systems. Regards, Kevin _______________________________________________ dev-commits-src-main@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/dev-commits-src-main To unsubscribe, send any mail to "dev-commits-src-main-unsubscr...@freebsd.org"
