TODO updated: * -Use background process to write dirty shared buffers to disk
--------------------------------------------------------------------------- Jan Wieck wrote: > 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. > > The configuration options controlling the process are all PGC_SIGHUP: > > # - Background writer - > #bgwriter_delay = 200 # 10-5000 milliseconds > #bgwriter_percent = 1 # 0-100% of dirty buffers > #bgwriter_maxpages = 100 # 1-1000 buffers max at once > > Delay is the number of milliseconds to wait between loops. If there was > nothing to do at all in one loop (all buffers clean), then the process > will sleep for 10 seconds. > > Percent is the percentage of "dirty pages" to write per loop. This is > independant of the size of the buffer pool. If percent = 0 the > postmaster will not start the process at all. > > Maxpages is an upper bound to prevent the background writer from > producing a write storm if a sequential operation causes all pages of a > large buffer pool to be dirtied at once. > > > Jan > > -- > #======================================================================# > # It's easier to get forgiveness for being wrong than for being right. # > # Let's break this rule - forgive me. # > #================================================== [EMAIL PROTECTED] # > > > ---------------------------(end of broadcast)--------------------------- > TIP 8: explain analyze is your friend > -- 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 8: explain analyze is your friend