 | | | high context switching and high load averages slowing down sy stem | high context switching and high load averages slowing down sy stem 2005-07-29 - By Magnus Andersen
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Here the lsmod output.
[root@(protected) root]# lsmod
Module Size Used by Not tainted
usbserial 23868 0 (autoclean) (unused)
lp 9156 0 (autoclean)
parport 38848 0 (autoclean) [lp]
autofs4 16888 0 (autoclean) (unused)
nfs 100276 2 (autoclean)
lockd 59600 1 (autoclean) [nfs]
sunrpc 89244 1 (autoclean) [nfs lockd]
audit 90808 3
e1000 78652 3
bonding 63364 1
floppy 57552 0 (autoclean)
sr_mod 17880 0 (autoclean)
microcode 6912 0 (autoclean)
ide-scsi 12528 0
ide-cd 34016 0
cdrom 32896 0 [sr_mod ide-cd]
loop 12728 0 (autoclean)
keybdev 2976 0 (unused)
mousedev 5688 0 (unused)
hid 22532 0 (unused)
input 6176 0 [keybdev mousedev hid]
usb-ohci 23208 0 (unused)
usbcore 81152 1 [usbserial hid usb-ohci]
ext3 89960 14
jbd 55156 14 [ext3]
lvm-mod 65568 33
sg 37324 0
qla2300 696316 6
qla2300_conf 301592 0
cciss 45188 3
sd_mod 14128 12
scsi_mod 115496 6 [sr_mod ide-scsi sg qla2300 cciss sd_mod]
[root@(protected) root]#
I'll post the top results during the next peak. The system do have
idle periods. Usage is in general never more than 15% when the system
performs. Below is also the 5 top waits from statspack during a peak.
Top 5 Timed Events
~~~~~~~~~~~~~~~~~~
CPU
db file sequential read
process startup
db file scattered read
log file parallel write
Thanks,
Magnus
On 7/28/05, Tom Sightler <ttsig@(protected)> wrote:
> On Thu, 2005-07-28 at 16:51 -0400, Magnus Andersen wrote:
> > Here is some information from vmstat, iostat, and dstat taken during
> > the last peak when I reached a load average ogf 13.
> >
> > vmstat 2 output:
> > procs memory swap io system
cpu
> > r b swpd free buff cache si so bi bo in cs us sy wa
id
> > 3 0 12156 21944 125688 2945324 0 0 20 178 368 289556 1 39
0 59
> > 8 0 12156 17740 125756 2947200 0 0 1060 184 579 284958 5 38
2 55
> > 5 0 12156 22316 125828 2944948 0 0 5798 190 315 276098 6 39
1 54
> > 3 0 12156 23200 125932 2945644 0 0 146 1154 576 288639 3 41
1 55
> > 3 0 12156 21584 125968 2945644 0 0 0 78 176 303064 1 38
0 61
>
> Wow, that is a lot of context switches. There is also a high amount of
> system time with very little user time, that would imply that this is
> not an issue with high Oracle usage, unless it's a problem with the SGA
> and shared memory. Any information on what waits your Oracle system is
> reporting during these low performance periods that might give us a
> little clue.
>
> My best guess is something else external, like a driver. Any
> possibility of a huge amount of network traffic during this time? Also,
> can you post which modules you have loaded and the output of "top -b >
> top.txt" during the event would be interesting.
>
> Does the system have periods of relative idle? What do your context
> switches look like during that period?
>
> Later,
> Tom
>
>
>
--
Magnus Andersen
Systems Administrator / Oracle DBA
Walker & Associates, Inc.
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