Strange "LAG" while using CP command

ps1x0 · 10-09-2011, 01:38 AM

Hey,

I'm currently using debian 6.0.2 and I get strange LAG while using the CP command.

The whole machine lags and especially the gameservers that are running on it (hlds, srcds).

Ping in the gameservers is normal, but it's laggy...

HDPARM result:

hdparm -Tt /dev/sdb

/dev/sdb:
Timing cached reads: 6356 MB in 2.00 seconds = 3179.15 MB/sec
Timing buffered disk reads: 178 MB in 3.01 seconds = 59.06 MB/sec

Sometimes speed is only 30 MB/sec. I don't think that that's normal?

I also noticed, that when I start XX servers, all of them start lagging.
I had no such problem while using debian 5. I'm using a custom kernel, but that shouldn't be the problem, since all of my other machines (still using debian 5) are with the same kernel config and they have no problems.

tronayne · 10-10-2011, 10:27 AM

Do you have gkrellm installed on that thing? If you do, start it and watch what it's telling you; if you don't install it from wherever you get distribution software (or http://members.dslextreme.com/users/...m/gkrellm.html).

By the way, on my quiescent system

Code:

hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   4314 MB in  2.00 seconds = 2157.02 MB/sec
 Timing buffered disk reads: 370 MB in  3.00 seconds = 123.29 MB/sec

Hope this helps some.

markseger · 10-10-2011, 12:42 PM

personally I think just looking at the time it takes to perform an operation and look at the average rate doesn't say too much. is the overloaded? how about interrupts? what's the network doing? could some other app be hogging the disk? if a real shot test, how about looking at these numbers every 0.1 second to see what's really happening, eg try collectl.

ideally you should run it continuously logging data to a file and when things slow down, play the data back and see what was going on.

-mark

syg00 · 10-10-2011, 05:05 PM

Maybe try latencytop. Be careful interpreting it though - my top guy at the moment is "opening cdrom device". Haven't used it in weeks .....

I suspect yours will be different.