I committed the first part of the background writer process. We had a consensus on attempting to avoid write() calls from regular backends, but did no come to any conclusions what to do to force the kernel to actually do some IO.
Consequently, this patch is a separate process launched by postmaster, that periodically write()'s out "some" dirty buffers in LRU order. This causes the buffers returned for replacement (when a backend needs to read in a page) to be clean allways. The process does no sync(), fsync() or any other calls thus far. Nothing has changed in the checkpoint logic either.
Can we have some idea where to tweak sync routines for comparing results?
I mean I would like to run pgbench with same config all along and compare the performance difference between sync, fsync and fdatasync etc.
If we could get to run any live world data test by that, it would be great as well.
Shridhar
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