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High System Time with Lock Contention in Pollwakeup (Doc ID 1662087.1)

Last updated on JUNE 18, 2017

Applies to:

Solaris Operating System - Version 10 1/13 U11 to 11.1 [Release 10.0 to 11.0]
Information in this document applies to any platform.

Symptoms

 When the issue happens, the system will see moderately high CPU system time.

/usr/bin/mpstat output

CPU minf mjf xcal  intr ithr   csw icsw migr smtx  srw syscl  usr sys  wt idl
  0   51   0  501 11984    7 25612    0  257   25    0   222    0  38   0  62
  1   71   0 1015 13524    3 24846    1  321   29    0    80   12  44   0  44
  2   43   0   21 13324    3 24896    1  244   16    0   580   10  45   0  45
  3   31   0  315 15194    3 28875    0  307   18    0    24    0  50   0  50
  4   17   0  712 15098    1 28676    0  327   24    0    35    0  50   0  50
  5   65   0  760 13035  105 25101    1  296   30    0   171    8  46   0  46
  6   25   0   20 14484    2 27597    0  286   19    0    45    0  48   0  52
  7    0   0   82 14123    1 26475    0  297   21    0    10    0  46   0  54

 

lockstat(1M) will show high lock contention in pollwakeup() with devpoll_clean_fd() in the stack.

/usr/sbin/lockstat -CcwP output

Adaptive mutex spin: 80968 events in 2.115 seconds (38285 events/sec)

-------------------------------------------------------------------------------
Count indv cuml rcnt     nsec Lock                   Hottest Caller         
10088  56%  56% 0.00   845310 0x30112202bb8          pollwakeup+0x178       

      nsec ------ Time Distribution ------ count     Stack                  
       512 |                               3         devpoll_clean_fd+0x28  
      1024 |                               8         closeandsetf+0x4c4     
      2048 |                               12        close+0x8              
      4096 |                               48        syscall_trap32+0xcc    
      8192 |@@                             887      
     16384 |@@@@                           1559     
     32768 |@@@@@@@                        2594     
     65536 |@@@@                           1504     
    131072 |@                              616      
    262144 |                               142      
    524288 |                               73       
   1048576 |@@@@@@@                        2494     
   2097152 |                               59       
   4194304 |                               13       
   8388608 |                               9        
  16777216 |                               7        
  33554432 |                               9        
  67108864 |                               20       
 134217728 |                               14       
 268435456 |                               16       
 536870912 |                               1        
-------------------------------------------------------------------------------

 

Cause

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In this Document
Symptoms
Cause
Solution
References

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