RHEL 6 CPU load

[-]

> What about the information from top? When comparing RHEL5 and RHEL6 systems,
> I would compare the total CPU usage of the server (out of 100% not 2400% or
> 1600%).
>
> Since the hardware is different, comparing a 16 named threads on a 16 core
> box at ???MHz against a 24 core box with 24 named threads at ???MHz may not
> necessarily be valid. If the CPUs are running at the same frequency (look at
> what speed they are actually running at vs the max speed... see
> /proc/cpuinfo ) then you can probably account for the 16 vs 24 core
> difference pretty easily. If the CPUs run at more than negligibly different
> frequencies you will have to factor that into any comparison or make the
> frequencies the same to make a 1:1 good comparison.

 The systems run at the exact same frequency processors (RHEL 6 -
X5675  @ 3.07GHz, RHEL 5 - X5667  @ 3.07GHz). One is just a little
older and only has 16 CPUs. I've run named on the RHEL 6 system with
only 16 procs (named -n 16) to see if it made a difference and the
result was the same, named on the RHEL 6 system running 6-7 times the
load of a RHEL 5 system.

We aren't running DNSSec so I don't think the managed-keys-directory
should be an issue.

Running a 30 second strace on one of the named threads shows the
process is a lot busier and has more errors on the RHEL 6 system:

RHEL 6:

> strace -c -p 29904
Process 29904 attached - interrupt to quit
Process 29904 detached
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 99.93    9.074464         135     67128     20375 futex
  0.04    0.003689           1      2538      2430 recvmsg
  0.02    0.002141           1      2498           write
  0.00    0.000256           2       103           sendmsg
  0.00    0.000138           4        36           socket
  0.00    0.000065           2        36           connect
  0.00    0.000019           0        72           setsockopt
  0.00    0.000000           0        36           close
  0.00    0.000000           0        36           bind
  0.00    0.000000           0        36           getsockopt
  0.00    0.000000           0       108           fcntl
------ ----------- ----------- --------- --------- ----------------
100.00    9.080772                 72627     22805 total

RHEL 5:

> strace -c -p 18498
Process 18498 attached - interrupt to quit
Process 18498 detached
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
 99.97    1.549134          69     22399      5604 futex
  0.02    0.000243           0       720       698 recvmsg
  0.01    0.000193           0       722           write
  0.00    0.000017           0        36           socket
  0.00    0.000000           0        36           close
  0.00    0.000000           0        36           connect
  0.00    0.000000           0        39           sendmsg
  0.00    0.000000           0        36           bind
  0.00    0.000000           0        72           setsockopt
  0.00    0.000000           0        36           getsockopt
  0.00    0.000000           0       108           fcntl
------ ----------- ----------- --------- --------- ----------------
100.00    1.549587                 24240      6302 total

Are others seeing the named process run at 130-180% on RHEL 6? We've
never seen this high of CPU usage for named on any system including a
Solaris 10 system running 32 CPUs. They have all run around 11-30% CPU
depending on the time of day.

--
Daniel