[CentOS] High load averages with latest kernel and USB drives?

Benjamin Smith lists at benjamindsmith.com
Wed Nov 18 23:11:35 UTC 2009


On Tuesday 17 November 2009 15:37:24 Todd Denniston wrote:
> Benjamin Smith wrote, On 11/17/2009 01:46 PM:
> > See comments below...
> >
> > On Tuesday 17 November 2009 07:52:01 Todd Denniston wrote:
> >> Benjamin Smith wrote, On 11/16/2009 10:56 PM:
> >>> I have a 1TB USB drive plugged into a USB2 port that I use to back up
> >>> the production drives (which are SCSI). It's working fine, but while
> >>> doing backups (hourly) the load average on the server shoots up from
> >>> the normal 0.5 - 1.5 or so up to a high between 10 and 30. Strangely,
> >>> even though the "load is high" the server is completely responsive,
> >>> even the USB drives being accessed are!
> >>>
> >>> Using top to diagnose, nothing seems to be particularly high! IoWait
> >>> seems reasonable (10-30%) and CPUs are 0.5%, Idle is 70-90%. Even
> >>> accessing the USB partition while the load is "high" is responsive!
> 
> you might add another field to top while you are watching, Last used cpu
>  (SMP), i.e., start top
> press f
> press j
> press enter
> 
> this should let you see if your process is bouncing between processors.

The process pg_dump is "adhering" fine to processor 1. I see usb-storage 
bouncing between processors - I've seen it on 3, 4, 7 over perhaps a minute. 
What could you recommend next? 

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