On Solaris you just look at the mount options on the file system and see if there is a forcedirectio option enabled. Generally since PostgreSQL doesn't use any special options for enabling directio that's a known way to figure it out on Solaris. Atleast on Solaris the performance over buffered filesystem is better for many workloads but not always. Plus you typically see a small reduction in CPU usage (system) and ofcourse memory.
However depending on workload, you may see increased latency in writes but generally that's not the problem in many workloads since its the multiple writes to the same file which is better using concurrentio (modified directio) in Solaris. As for Linux I will leave that to other experts .. -Jignesh lai yoke hman wrote: > Hello, > How can I know my PostgreSQL 8 is using direct I/O or buffered I/O? If using > buffered I/O, how can I enable direct I/O? What is the performance difference > of them? > This is urgent, Thanks. > _________________________________________________________________ > Windows Live Spaces is here! It’s easy to create your own personal Web site. > http://spaces.live.com/?mkt=en-my > > ---------------------------(end of broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings > ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
