| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Jan Wieck <JanWieck(at)Yahoo(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Stark <gsstark(at)mit(dot)edu>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Experimental patch for inter-page delay in VACUUM |
| Date: | 2003-11-10 14:25:49 |
| Message-ID: | 200311101425.hAAEPnE10962@candle.pha.pa.us |
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| Thread: | |
| Lists: | pgsql-hackers |
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(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
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