On Jan 15, 2012, at 8:13 PM, Greg Smith wrote: > On 01/15/2012 04:17 PM, Heikki Linnakangas wrote: >> I think it makes more sense to use the max read rate as the main knob, >> rather than write rate. That's because the max read rate is higher than the >> write rate, when you don't need to dirty pages. Or do you think saturating >> the I/O system with writes is so much bigger a problem than read I/O that it >> makes more sense to emphasize the writes? > > I haven't had the I/O rate logging available for long enough to have a good > feel for which is more important to emphasize. I'm agnostic on this. I'd > have no problem accepting the argument that exposing the larger of the two > rates--which is the read one--makes for a cleaner UI. Or that it is the one > more like other knobs setting precedents here.
Could we expose both? On our systems writes are extremely cheap... we don't do a ton of them (relatively speaking), so they tend to just fit into BBU cache. Reads on the other hard are a lot more expensive, at least if they end up actually hitting disk. So we actually set page_dirty and page_hit the same. -- Jim C. Nasby, Database Architect j...@nasby.net 512.569.9461 (cell) http://jim.nasby.net -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
