1. 18 Jun, 2009 1 commit
    • Keika Kobayashi's avatar
      softirq: introduce statistics for softirq · aa0ce5bb
      Keika Kobayashi authored
      Statistics for softirq doesn't exist.
      It will be helpful like statistics for interrupts.
      This patch introduces counting the number of softirq,
      which will be exported in /proc/softirqs.
      
      When softirq handler consumes much CPU time,
      /proc/stat is like the following.
      
      $ while :; do  cat /proc/stat | head -n1 ; sleep 10 ; done
      cpu  88 0 408 739665 583 28 2 0 0
      cpu  450 0 1090 740970 594 28 1294 0 0
                                    ^^^^
                                   softirq
      
      In such a situation,
      /proc/softirqs shows us which softirq handler is invoked.
      We can see the increase rate of softirqs.
      
      <before>
      $ cat /proc/softirqs
                      CPU0       CPU1       CPU2       CPU3
      HI                 0          0          0          0
      TIMER         462850     462805     462782     462718
      NET_TX             0          0          0        365
      NET_RX          2472          2          2         40
      BLOCK              0          0        381       1164
      TASKLET            0          0          0        224
      SCHED         462654     462689     462698     462427
      RCU             3046       2423       3367       3173
      
      <after>
      $ cat /proc/softirqs
                      CPU0       CPU1       CPU2       CPU3
      HI                 0          0          0          0
      TIMER         463361     465077     465056     464991
      NET_TX            53          0          1        365
      NET_RX          3757          2          2         40
      BLOCK              0          0        398       1170
      TASKLET            0          0          0        224
      SCHED         463074     464318     464612     463330
      RCU             3505       2948       3947       3673
      
      When CPU TIME of softirq is high,
      the rates of increase is the following.
        TIMER  : 220/sec     : CPU1-3
        NET_TX : 5/sec       : CPU0
        NET_RX : 120/sec     : CPU0
        SCHED  : 40-200/sec  : all CPU
        RCU    : 45-58/sec   : all CPU
      
      The rates of increase in an idle mode is the following.
        TIMER  : 250/sec
        SCHED  : 250/sec
        RCU    : 2/sec
      
      It seems many softirqs for receiving packets and rcu are invoked.  This
      gives us help for checking system.
      Signed-off-by: default avatarKeika Kobayashi <kobayashi.kk@ncos.nec.co.jp>
      Reviewed-by: default avatarHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
      Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Eric Dumazet <dada1@cosmosbay.com>
      Cc: Alexey Dobriyan <adobriyan@gmail.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      aa0ce5bb
  2. 17 Jun, 2009 39 commits