I have two identical servers (or so I am told), but application work is
running 2-3 times slower on one than the other. Using Tanel's snapper, I
see that all active sessions are all on CPU. Viewing top shows me the same
thing, each session pegs a cpu. We also found that it wasn't particular SQL
that slowed down across severs, but it looked like everything was slow. A
select count(*) from dba_objects showed this behavior as did Jonathan
Lewis's kill_cpu script. This gave me something to test with. Running a
10046, I saw the same amount of resource utilization (parse count, fetch
count, cr count, ...), no contention (wait events), but one server finished
2.5 times faster than the other. Looking at session stats through snapper,
I see that the number of session logical reads per sec (~all of which are
consistent reads) is ~ 2.5 times higher on one server than the other. That
explains why it takes one longer to finish.
So, now what?? Why is one server giving me 350k consistent gets/per second
and the other is ~800k? Is it hardware? /proc/cpuinfo shows the same cpu
for each box. Is it hidden in the Oracle code path? I realize that not all
LIO are created equal, but how do I check this? I am running on SE12.1.0.1
Any and all thoughts welcome.
Henry
