Jan Wieck wrote: > Bruce Momjian wrote: > > > 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. > > > > It looks as if you're assuming that I am making the backends unable to > write on their own, so that they have to wait on the checkpointer. I > never said that.
Maybe I missed it but are those backend now doing write or write/fsync? If the former, that is fine. If the later, it does seem slower than it used to be. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
