On Sat, 2007-03-10 at 23:26 +1300, Mark Kirkwood wrote: > Simon Riggs wrote: > > New patch enclosed, implementation as you've requested. > > > > Not ready to apply yet, but good for testing. > > > > A quick test using the setup for "Buffer cache is not scan resistant" > thread: > > Firstly vanilla 8.3 from 20070310: > > Shared Buffers Elapsed vmstat IO rate > -------------- ------- -------------- > 400MB 101 s 122 MB/s > 128KB 79 s 155 MB/s [1] > > Now apply cycle scan v2: > > Shared Buffers Scan_recycle_buffers Elapsed vmstat IO rate > -------------- -------------------- ------- ------------- > 400MB 0 101 s 122 MB/s > 400MB 8 78 s 155 MB/s > 400MB 16 77 s 155 MB/s > 400MB 32 78 s 155 MB/s > 400MB 64 82 s 148 MB/s > 400MB 128 93 s 128 MB/s > > Certainly seems to have the desired effect! > > Cheers > > Mark > > [1] I'm not seeing 166 MB/s like previous 8.2.3 data, however 8.3 PGDATA > is located further toward the end of the disk array - which I suspect is > limiting the IO rate a little.
That's good news, thanks very much for testing that. Before we can claim success, we need a few more tests on VACUUM, COPY and a null test case to show it doesn't effect typical workloads, except to improve vacuuming. I'll see if we can arrange those at EDB on a reasonable size system. -- Simon Riggs EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
