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 -- Todd Denniston Crane Division, Naval Surface Warfare Center (NSWC Crane) Harnessing the Power of Technology for the Warfighter _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos