[clug] dual opteron performance problem

Wed Dec 15 05:51:59 GMT 2004

On Wed, Dec 15, 2004 at 03:14:55PM +1100, Rob Shugg wrote:
> Guys
> I am trying to determine what is limiting the performance of my debian 
> Opteron box. It has two cpus and a two sata disc software raid 1 array. the 
> system boots from an ide drive.
> 
> We are using the system as a vmware host for a couple of vmware debian 
> guests.
> as soon as we load up one of the virtual servers the system bogs down and 
> becomes unusable.
> 
> the thing is, the CPU idle time rarely gets below 90% see the stats below, 
> I'd appreciate any suggestions as to how to pinpoint the problem.
> I have heard a few snippets about sata not being as good as promised, could 
> that be an issue?

Having recently had a play with a VMWare trial myself, I found that the
default configuration basically offered itself almost all of my system
memory for all the virtual machines, and even if any given virtual
machine was set to use well below the physical RAM, VMware would malloc
the entire allowance. I looked away, looked back, and between VMWare
(and I think mysqld?) my server started swapping and I had to kill it.
>_<

Certainly, the below top output suggests this isn't a problem for you,
but certainly having one 'R' and everything else 'D' (which if I
understand correctly is one running process, and the rest spinning on
I/O), it's worth noting that VMWare has both a "per-guest" memory
setting, and a "all guests" memory setting which, at least here, could
only be set in /etc/vmware/config by root, either running the interface
as root -_-;, or adding the following lines:

prefvmx.useRecommendedLockedMemSize = "FALSE"
prefvmx.allVMMemoryLimit = "200"

Don't let that number get too low, or things will start swapping. The
above was enough to allow a single 128MB machine run at once. I didn't
try both. It defaulted much higher, obviously. Experimentation with my
laptop suggested about 40MB of RAM overhead was needed over the guest
memory allowance, or it'd start swapping and kill the machine's
responsiveness.

(This is with a Debian/sarge RC2 guest on Debian/unstable + linux 2.6.9
hosts)

I hope you do get this working, since my next laptop will hopefully be
an AMD64, and I'd love to be able to VMWare up the included XP license
without shutting down linux. I originally grabbed the VMWare trial to
try and boot the Win98 installed on the hard disk, but haven't gotten
that working yet. ^_^

> rob

> load with the virtual machines idling:
> ----------------------------------------
> top - 13:29:50 up 73 days, 22:11,  2 users,  load average: 0.05, 0.12, 0.27
> Tasks: 176 total,   1 running, 175 sleeping,   0 stopped,   0 zombie
> Cpu(s):   1.0% user,   2.6% system,   0.0% nice,  96.4% idle
> Mem:   1033492k total,  1007636k used,    25856k free,    26256k buffers
> Swap:  1967944k total,   182912k used,  1785032k free,   859284k cached
> 
>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>  1814 root      17   0   776  716  504 S  1.0  0.1 892:28.98 top
>  7340 vmware    12 -10 10484 6016 5796 S  1.0  0.6 301:27.41 vmware-vmx
> 27471 root      17   0   756  688  500 S  1.0  0.1 408:18.46 top
> 
> Load with one vm doing some dumping and loading some mysql data:
> ----------------------------------------------------------------
> top - 13:45:56 up 73 days, 22:27,  2 users,  load average: 9.27, 3.44, 1.38
> Tasks: 183 total,   1 running, 181 sleeping,   0 stopped,   1 zombie
> Cpu(s):   1.6% user,   7.7% system,   0.0% nice,  90.8% idle
> Mem:   1033492k total,  1020476k used,    13016k free,     8008k buffers
> Swap:  1967944k total,   184776k used,  1783168k free,   909336k cached
> 
>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 11717 rob       15   0   740  676  512 R  2.9  0.1   0:17.01 top
> 23629 vmware     6 -10  183m 180m 180m D  0.7 17.9   2:38.36 vmware-vmx
> 23630 vmware     6 -10  183m 180m 180m D  0.7 17.9   2:37.63 vmware-vmx
>     7 root       9   0     0    0    0 D  0.3  0.0  37:50.63 kupdated
> 23631 vmware     5 -10  183m 180m 180m D  0.3 17.9   2:38.26 vmware-vmx
>     9 root       9   0     0    0    0 D  0.0  0.0  36:02.89 kjournald
>   247 root       9   0     0    0    0 D  0.0  0.0 129:27.57 kjournald
>   634 root       9   0  1772  372  372 D  0.0  0.0   5:00.56 snmpd
>   440 rob        9   0  2856 1024 1024 D  0.0  0.1   5:34.66 korgac
> 23627 vmware     5 -10  183m 180m 180m D  0.0 17.9   2:38.05 vmware-vmx
> 23628 vmware     5 -10  183m 180m 180m D  0.0 17.9   2:38.50 vmware-vmx
> 11030 root       9   0  1560  540  540 D  0.0  0.1   0:00.27 smbd

> rob at k9:~$ iostat
> Linux 2.4.27 (k9)       15/12/04
> 
> avg-cpu:  %user   %nice    %sys %iowait   %idle
>            1.21    0.20    3.08    0.00   95.51
> 
> Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
> sda               7.55       547.48       340.46 3497371076 2174872016
> sdb               7.57       550.70       340.46 3517943864 2174872016
> hda               2.00         9.92        25.22   63391716  161095336
> hda1              1.03         5.31        11.77   33903026   75176536
> hda2              0.75         0.84        11.40    5353466   72801576
> hda3              0.21         3.78         2.05   24135192   13117224

-- 
-----------------------------------------------------------
Paul "TBBle" Hampson, MCSE
7th year CompSci/Asian Studies student, ANU
The Boss, Bubblesworth Pty Ltd (ABN: 51 095 284 361)
Paul.Hampson at Anu.edu.au

"No survivors? Then where do the stories come from I wonder?"
-- Capt. Jack Sparrow, "Pirates of the Caribbean"

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