Re: Checkpointer write combining

Hi all,

With reference to the last patches (v11) I received [1] and while reviewing Melanie’s latest feedback, I understood that PageSetBatchChecksumInplace() is currently WIP and depends on upcoming changes to hint-bit locking. It will be contrary to the flow if I propose new functional changes to checksum batching at this time. So for now I will focus on preparatory or documentation improvements until I get the updates on dependencies.
Regarding my patch attached, the patch introduces write-combining during checkpoints by batching contiguous buffers and allowing them to be written using vectorized I/O. My patch includes write-combining for checkpoint buffer flushes, contiguous buffer batching, Preserved WAL ordering, locking, and buffer state invariants. The change is currently limited to the checkpointer path (BufferSync()). So far I tested my implementation and found that all the regression (233 tests) and isolation tests (121 tests) got passed, the manual pgbench validation completed successfully and also verified pg_stat_bgwriter counters before and after checkpoints. So far the implementation is stable in my system. And currently, I am focussing on the implementation of check pointer write combining for bgwriter behavior and will update it soon after validating my implementation.