On Sat, Jan 14, 2023 at 12:34 PM Andres Freund <and...@anarazel.de> wrote:
> Hi, > > On 2023-01-14 00:48:52 -0800, Jeff Davis wrote: > > On Mon, 2022-12-26 at 14:20 +0530, Bharath Rupireddy wrote: > > > Please review the attached v2 patch further. > > > > I'm still unclear on the performance goals of this patch. I see that it > > will reduce syscalls, which sounds good, but to what end? > > > > Does it allow a greater number of walsenders? Lower replication > > latency? Less IO bandwidth? All of the above? > > One benefit would be that it'd make it more realistic to use direct IO for > WAL > - for which I have seen significant performance benefits. But when we > afterwards have to re-read it from disk to replicate, it's less clearly a > win. > +1. Archive modules rely on reading the wal files for PITR. Direct IO for WAL requires reading these files from disk anyways for archival. However, Archiving using utilities like pg_receivewal can take advantage of this patch together with direct IO for WAL. Thanks, Satya
