> I performed some simple tests, and I'll show the results below.
> (1) The default case > 235 80 226 77 240 > (2) No write case > 242 250 244 253 280 > (3) No checkpoint case > 229 252 256 292 276 > (4) No fsync() case > 236 112 215 216 221 > (5) No write by PostgreSQL, but fsync() by another program case > 9 223 260 283 292 > (6) case (5) + O_SYNC by write_fsync > 97 114 126 112 125 > (7) O_SYNC case > 182 103 41 50 74
I posted a patch to PATCHES. Please try out it. It does write() smoothly, but fsync() at a burst. I suppose the result will be between (3) and (5).
Itagaki,
Did you had a chance to look into this any further? We, at EnterpriseDB, have done some testing on this patch (dbt2 runs) and it looks like we are getting the desired results, particularly so when we spread out both sync and write phases.