2 Replies Latest reply: May 5, 2010 8:09 AM by 807559 RSS

    CPU Usage

    807559
      I have a question posed to me by an Oracle DBA who raised concerns that 2 virtual CPU cores are steady at about 94% idle while the 4 main cores are about 85% idle. The "top" command says the system has a load of about 3 to 4 and is about 50% idle. I figured the system would onlu\y use what it needed but the DBA insisted the idle times should be load balanced to have exactly the same idle times across all 6 CPUs. I have added some output to view. My question is this. Is the 95% idle time on the 2 virtual cores considered normal? If not, what could I do to better balance the CPU load?

      TOP OUTPUT
      last pid: 15493; load averages: 2.72, 3.14, 3.42 16:03:40
      1371 processes:1363 sleeping, 2 running, 6 on cpu
      CPU states: 52.7% idle, 38.0% user, 8.7% kernel, 0.6% iowait, 0.0% swap
      Memory: 40G real, 16G free, 21G swap in use, 43G swap free

      PID USERNAME LWP PRI NICE SIZE RES STATE TIME CPU COMMAND
      12879 oracle 1 0 11 64M 44M run 31:37 16.31% frmweb
      398 root 1 29 0 1968K 904K cpu/0 20.4H 2.53% praudit
      396 root 2 19 0 2688K 1432K cpu/1 812:40 1.64% snarecore
      215 root 30 59 0 4024K 3024K sleep 337:27 0.63% nscd
      19255 oracle 1 26 11 56M 37M sleep 1:08 0.44% frmweb
      11688 oracle 1 19 11 42M 24M sleep 0:05 0.42% frmweb
      15179 oracle 1 26 11 40M 22M sleep 0:08 0.42% frmweb
      698 oracle 436 26 11 523M 370M sleep 8:42 0.41% java
      12627 oracle 1 39 0 4144K 2480K sleep 1:00 0.39% top
      15275 root 1 39 0 4096K 2512K cpu/16 0:04 0.39% top
      11509 oracle 1 0 11 52M 34M run 1:13 0.37% frmweb
      9445 oracle 1 16 11 61M 42M sleep 1:15 0.31% frmweb
      694 oracle 433 26 11 459M 306M sleep 9:51 0.29% java
      27107 oracle 1 26 11 47M 29M sleep 0:50 0.29% frmweb
      12787 oracle 1 26 11 52M 33M sleep 0:29 0.28% frmweb

      TROVIASPROD4:/ #psrinfo
      0 on-line since 04/11/2010 15:38:19
      1 on-line since 04/11/2010 15:38:19
      2 on-line since 04/11/2010 15:38:19
      3 on-line since 04/11/2010 15:38:14
      16 on-line since 04/22/2010 08:55:13
      17 on-line since 04/22/2010 08:55:20
      18 off-line since 04/11/2010 15:38:46
      19 off-line since 04/11/2010 15:38:46

      TROVIASPROD4:/ #mpstat -p
      CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl set
      0 79 0 1567 1869 253 1679 130 94 606 1 573 11 4 1 84 0
      1 84 0 1557 1833 1 1621 138 99 543 1 267 11 3 1 85 0
      2 83 0 1712 337 237 1676 111 94 683 1 742 12 4 1 84 0
      3 92 0 1422 435 216 1628 134 94 602 1 454 11 3 0 85 0
      16 33 0 809 50 18 720 30 43 247 0 2111 4 1 0 *94* 0 <--------idle time in question
      17 37 0 842 32 1 691 31 45 233 0 1982 5 1 0 *94* 0 <--------idle time in question
        • 1. Re: CPU Usage
          user4994457
          TAdriver wrote:
          I have a question posed to me by an Oracle DBA who raised concerns that 2 virtual CPU cores are steady at about 94% idle while the 4 main cores are about 85% idle.
          What do you mean by a "virtual core" and a "main core"? The items you are looking at are "virtual CPUs

          What is the hardware in question? Can you show "psrinfo -vp" output?
          The "top" command says the system has a load of about 3 to 4 and is about 50% idle. I figured the system would onlu\y use what it needed but the DBA insisted the idle times should be load balanced to have exactly the same idle times across all 6 CPUs.
          Depends.
          Interrupts are not sent to all CPUs, so that can cause some differences. Processor affinity could affect things short term, but it shouldn't be consistent. Also, you've disabled two virtual CPUs. Depending on the relationship, some CPU cores might not be loaded the same way.

          I have added some output to view. My question is this. Is the 95% idle time on the 2 virtual cores considered normal? If not, what could I do to better balance the CPU load?
          >
          TOP OUTPUT
          last pid: 15493; load averages: 2.72, 3.14, 3.42 16:03:40
          1371 processes:1363 sleeping, 2 running, 6 on cpu
          CPU states: 52.7% idle, 38.0% user, 8.7% kernel, 0.6% iowait, 0.0% swap
          Memory: 40G real, 16G free, 21G swap in use, 43G swap free

          PID USERNAME LWP PRI NICE SIZE RES STATE TIME CPU COMMAND
          12879 oracle 1 0 11 64M 44M run 31:37 16.31% frmweb
          398 root 1 29 0 1968K 904K cpu/0 20.4H 2.53% praudit
          396 root 2 19 0 2688K 1432K cpu/1 812:40 1.64% snarecore
          215 root 30 59 0 4024K 3024K sleep 337:27 0.63% nscd
          19255 oracle 1 26 11 56M 37M sleep 1:08 0.44% frmweb
          11688 oracle 1 19 11 42M 24M sleep 0:05 0.42% frmweb
          15179 oracle 1 26 11 40M 22M sleep 0:08 0.42% frmweb
          698 oracle 436 26 11 523M 370M sleep 8:42 0.41% java
          12627 oracle 1 39 0 4144K 2480K sleep 1:00 0.39% top
          15275 root 1 39 0 4096K 2512K cpu/16 0:04 0.39% top
          11509 oracle 1 0 11 52M 34M run 1:13 0.37% frmweb
          9445 oracle 1 16 11 61M 42M sleep 1:15 0.31% frmweb
          694 oracle 433 26 11 459M 306M sleep 9:51 0.29% java
          27107 oracle 1 26 11 47M 29M sleep 0:50 0.29% frmweb
          12787 oracle 1 26 11 52M 33M sleep 0:29 0.28% frmweb

          TROVIASPROD4:/ #psrinfo
          0 on-line since 04/11/2010 15:38:19
          1 on-line since 04/11/2010 15:38:19
          2 on-line since 04/11/2010 15:38:19
          3 on-line since 04/11/2010 15:38:14
          16 on-line since 04/22/2010 08:55:13
          17 on-line since 04/22/2010 08:55:20
          18 off-line since 04/11/2010 15:38:46
          19 off-line since 04/11/2010 15:38:46

          TROVIASPROD4:/ #mpstat -p
          CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl set
          0 79 0 1567 1869 253 1679 130 94 606 1 573 11 4 1 84 0
          1 84 0 1557 1833 1 1621 138 99 543 1 267 11 3 1 85 0
          2 83 0 1712 337 237 1676 111 94 683 1 742 12 4 1 84 0
          3 92 0 1422 435 216 1628 134 94 602 1 454 11 3 0 85 0
          16 33 0 809 50 18 720 30 43 247 0 2111 4 1 0 *94* 0 <--------idle time in question
          17 37 0 842 32 1 691 31 45 233 0 1982 5 1 0 *94* 0 <--------idle time in question
          Instead of disabling 18 and 19, I might try disabling 3 and 19 and see what the response looks like.

          --
          Darren
          • 2. Re: CPU Usage
            807559
            Hey Darren, thanks for clearing up my misunderstanding of virtual cores. I see what you are talking about. I have set my startup script to ensure processors 0, 1, 2, 16, 17 and 18 are brought on-line and 3 and 19 are set to off-line. The business need with licensing is the reason we have 2 CPUs in the off-line state. Of course, I'll have to wait till the next available reboot time for this but at least it should be as solid as it can get from the admin side.