On the other hand, I would complicate matters by having a different parameter, say:
AUTOTUNELRU 1/0 # To enable or disable auto LRU tuning
and having yet another onmode option to dynamically enable/disable it at the discretion of the DBA.
Our goal over time has been to replace manual knobs with autonomics wherever it made sense to us, so it's a little painful to go in the opposite direction, but we'll consider bumping up IFMX-I-455. Meanwhile I'm going to trust you guys with an undocumented, unsupported feature that should allow you to do exactly what you're asking for. I have not personally tested this method in a benchmark and cannot vouch for it in a production environment, but I see no reason to warn you off of it for test systems because it makes use of the same internal routines that automatic LRU tuning uses. If you try this and let me know whether it works for you, hacky as it is, that will inform decisions we eventually make on IFMX-I-455.This method assumes you're beginning with AUTO_LRU_TUNING off. Say you want to set lru_min to 10 and lru_max to 20 for all buffer pools:onmode -wm AUTO_LRU_TUNING="1,min=10,max=20"onmode -wm AUTO_LRU_TUNING=0Note that even though we finish with AUTO_LRU_TUNING off again, the new min and max settings should remain. Check with onstat -R.Say you want to customize lru_min and lru_max for a specific buffer pool. Again these commands will only work if AUTO_LRU_TUNING is off to begin with:onmode -wm AUTO_LRU_TUNING="1,bpool=0,min=60,max=70"onmode -wm AUTO_LRU_TUNING=0Note that buffer pools are numbered 0-7 on 2k systems and 0-3 on 4k systems. Pool numbers are fixed for the different page sizes. I.e. on a 2k system even if you have only two buffer pools: a 2k pool and a 16k pool, their numbers are 0 and 7, respectively.I hope you find the automatic tuning algorithm works as well as manual tuning in terms of I/O, checkpoint, and overall performance. If manual tuning is significantly better in some scenario though, I'd be interested to hear about it. Have fun and send feedback to me or your customer advocate if you have one.-jc
Add bpool=0-7 or 0-4 ( divided bufferpool size by page size)
onmode -wm AUTO_LRU_TUNING="1,bpool=0,min=5,max=10"
informix@aragorn[live]: onstat -R | egrep "(^start|^ .*[1-9])"
start clean at 10.000% (of pair total) dirty, or 781 buffs dirty, stop at
start clean at 60.000% (of pair total) dirty, or 586 buffs dirty, stop at
start clean at 60.000% (of pair total) dirty, or 281 buffs dirty, stop at