On Fri, 6 Dec 2024 at 10:54, devanga.susmi...@fujitsu.com < devanga.susmi...@fujitsu.com> wrote:
> Hello, This email is to discuss the contribution of the speed-up > popcount and popcount mask feature we have developed for the ARM > architecture using SVE intrinsics. > The current method for popcount on ARM relies on compiler intrinsics or C > code, which processes data in a scalar fashion, handling one integer at a > time. By leveraging SVE intrinsics for popcount, the execution can process > multiple integers simultaneously, depending on the vector length, thereby > significantly enhancing the performance of the functionality. > We have designed this feature to ensure compatibility and robustness. It > includes compile-time and runtime checks for SVE compatibility with both > the compiler and hardware. If either check fails, the code falls back to > the existing scalar implementation, ensuring fail-safe operation. > Additionally, we leveraged the existing infrastructure to select between > different popcount implementations, avoiding additional complexity. > > *Algorithm Overview:* > 1. For larger inputs, align the buffers to avoid double loads. For smaller > inputs alignment is not necessary and might even degrade the performance. > 2. Process the aligned buffer chunk by chunk till the last incomplete > chunk. > 3. Process the last incomplete chunk. > *Our setup:* > Machine: AWS EC2 c7g.8xlarge - 32vcpu, 64gb RAM > OS : Ubuntu 22.04.5 LTS > GCC: 11.4 > > *Benchmark and Result:* > We have used John Naylor's popcount-test-module [0] for benchmarking and > observed a speed-up of more than 3x for larger buffers. Even for smaller > inputs of size 8 and 32 bytes there aren't any performance degradations > observed. > > > > We would like to contribute our above work so that it can be available for > the community to utilize. To do so, we are following the procedure > mentioned in Submitting a Patch - PostgreSQL wiki > <https://wiki.postgresql.org/wiki/Submitting_a_Patch>. *Please find the > attachments for the patch and performance results.* > Please let us know if you have any queries or suggestions. > > > Thanks & Regards, > Susmitha Devanga. > Hi! Is this patch somehow related to [0] ? [0] https://www.postgresql.org/message-id/010101936e4aaa70-b474ab9e-b9ce-474d-a3ba-a3dc223d295c-000000%40us-west-2.amazonses.com -- Best regards, Kirill Reshke
