Hi, In commit 3eb77eba we made it possible for any subsystem that wants a file to be flushed as part of the next checkpoint to ask the checkpointer to do that, as previously only md.c could do.
In the past, foreground CLOG flush stalls were a problem, but then commit 33aaa139 cranked up the number of buffers, and then commit 5364b357 cranked it right up until the flushes mostly disappeared from some benchmark workload but not so high that the resulting linear searches through the buffer array destroyed the gains. I know there is interest in moving that stuff into regular shared buffers, so it can be found via the buffer mapping system (and improve as that improves), written back by the background writer (and improve as that improves), managed with a proper replacement algorithm (and improve as that improves), etc etc. That sounds like a great idea to me, but it's a big project. In the meantime, one thing we could do is hand off the fsyncs, but I'm not sure if it's still considered a real problem in the field given the new parameters. Anyway, I had a patch for that, that I used while testing commit 3eb77eba. While reading old threads about SLRU today I found that several people had wished for a thing exactly like that, so I dusted it off and rebased it.
0001-Use-the-checkpointer-to-fsync-SLRU-files.patch
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