Benjamin Smith wrote, On 11/18/2009 06:11 PM:
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?
try #2 set the usb-storage on a particular set of processors, # Note USBSTORPID= line prototyped on CentOS 5 machine not 4. USBSTORPID=`ps aux |grep usb-storage|head -1 |awk '{print $2}'` taskset -p -c 4 $USBSTORPID
and still I have not had the taskset of the USB driver cause faults when used on a dual processor Xeon, but if any of the above breaks your system you get to keep the chunky bits. :0
so if you try it, keep an eye on it. reversing the above taskset in your case would I _think_ be: taskset -p -c 0-7 $USBSTORPID