Hi Stefan,
Fair enough, I was aware that I was oversimplifying as I was just dashing off a
quick email, and perhaps simplified too much :-)
Clearly there are other 'normal' wait states that sessions can be in. Log File
Sync being a big one that springs to mind.
Still I find the ratio of IO to CPU to be a good enough rule of thumb to get
you started, and the real answers come from testing as each app will be
slightly different.
I should have been clearer that I was suggesting a 'starting point' for testing
and not a hard limit. Still this is better IMO, than the opposite of starting
way to high, and tuning down the way (or more likely, up the way) when you
start to get connection pool exhaustion.
Chris
-----Original Message-----
From: Stefan Koehler [mailto:contact@xxxxxxxx]
Sent: 18 April 2016 16:46
To: Osborne, Chris <Chris.Osborne@xxxxxx>; cstephens16@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: RE: CPU Wait troubleshoot
Hello Christopher,
My understanding of the RWP recommendation is that max session should
be between 1 and 10 times the number of cores, depending on the percentage
time spent on IO versus CPU for your app.
On the rare occasions when we get in early and have time for full
testing, I like to have each app server with a connection pool set very low,
and then test for performance versus requirement, and then only go up the way
if we don't meet the requirements.
"Osborne, Chris" <Chris.Osborne@xxxxxx> hat am 18. April 2016 um 16:29Information in this email including any attachments may be privileged,
geschrieben:
My understanding of the RWP recommendation is that max session should
be between 1 and 10 times the number of cores, depending on the percentage
time spent on IO versus CPU for your app.
On a 32 Core system, 320 sessions max, if they are IO intensive.
However, if each session is roughly 50/50 on IO versus CPU, you'll probably
want a smaller number than 320. As always, testing is your friend.
On the rare occasions when we get in early and have time for full
testing, I like to have each app server with a connection pool set very low,
and then test for performance versus requirement, and then only go up the way
if we don't meet the requirements.
Christopher Osborne
