Re: Experimental patch for inter-page delay in VACUUM

Jan Wieck wrote:
> Bruce Momjian wrote:
> 
> > Now, O_SYNC is going to force every write to the disk.  If we have a
> > transaction that has to write lots of buffers (has to write them to
> > reuse the shared buffer)
> 
> So make the background writer/checkpointer keeping the LRU head clean. I 
> explained that 3 times now.

If the background cleaner has to not just write() but write/fsync or
write/O_SYNC, it isn't going to be able to clean them fast enough.  It
creates a bottleneck where we didn't have one before.

We are trying to eliminate an I/O storm during checkpoint, but the
solutions seem to be making the non-checkpoint times slower.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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