John Naylor 37a6e5df37 Optimize xid/subxid searches in XidInMVCCSnapshot(). ... As reported by Yura Sokolov, scanning the snapshot->xip array has noticeable impact on scalability when there are a large number of concurrent writers. Use the optimized (on x86-64) routine from b6ef16756 to speed up searches through the [sub]xip arrays. One benchmark showed a 5% increase in transaction throughput with 128 concurrent writers, and a 50% increase in a pathological case of 1024 writers. While a hash table would have scaled even better, it was ultimately rejected because of concerns around code complexity and memory allocation. Credit to Andres Freund for the idea to optimize linear search using SIMD instructions. Nathan Bossart Reviewed by: Andres Freund, John Naylor, Bharath Rupireddy, Masahiko Sawada Discussion: https://postgr.es/m/20220713170950.GA3116318%40nathanxps13		2022-08-11 09:17:42 +07:00
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combocid.c	Update copyright for 2022	2022-01-07 19:04:57 -05:00
Makefile	Split all OBJS style lines in makefiles into one-line-per-entry style.	2019-11-05 14:41:07 -08:00
snapmgr.c	Optimize xid/subxid searches in XidInMVCCSnapshot().	2022-08-11 09:17:42 +07:00