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top - 21:02:03 up 28 days,  7:34,  1 user,  load average: 1.00, 1.01, 1.05
Tasks:  95 total,   2 running,  93 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.4%us, 13.8%sy,  0.0%ni, 81.6%id,  3.2%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   1022992k total,   652100k used,   370892k free,    93248k buffers
Swap:  2031612k total,    55960k used,  1975652k free,   115312k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND            
  904 root      20   0 11180 1028  624 R 98.5  0.1 322:03.46 vpnc  


> ltrace -f -t -p 904

doesn't output anything

output of vmstat 1

procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  0  55960 232964  98284 242440    0    0     4    58    8    4  1 14 82  3  0
 1 0  55960 232956  98284 242464    0    0     0     0 1014   36  6 94  0  0  0
 1  0  55960 232956  98284 242464    0    0     0     0 1012   36  7 93  0  0  0
 1  0  55960 232956  98284 242464    0    0     0    28 1022   58  6 94  0  0  0
 1  0  55960 232956  98284 242464    0    0     0     0 1013   37  8 92  0  0  0
 1  0  55960 232956  98284 242464    0    0     0     0 1013   40  6 94  0  0  0
 1  0  55960 232956  98284 242464    0    0     0     0 1018   54  7 93  0  0  0
 1  0  55960 232956  98284 242464    0    0     0     0 1011   40  8 92  0  0  0
 1  0  55960 232956  98284 242464    0    0     0     0 1012   34  9 91  0  0  0
 1  0  55960 232956  98284 242464    0    0     0     0 1014   46  8 92  0  0  0
 1  0  55960 232956  98284 242464    0    0     0     0 1017   42  9 91  0  0  0

strace -p 904

select(7, [3 4 6], NULL, NULL, {295, 0}) = 1 (in [6], left {294, 999997})
select(7, [3 4 6], NULL, NULL, {295, 0}) = 1 (in [6], left {294, 999997})
select(7, [3 4 6], NULL, NULL, {295, 0}) = 1 (in [6], left {294, 999997})
select(7, [3 4 6], NULL, NULL, {295, 0}) = 1 (in [6], left {294, 999997})
select(7, [3 4 6], NULL, NULL, {295, 0}) = 1 (in [6], left {294, 999997})
select(7, [3 4 6], NULL, NULL, {295, 0}) = 1 (in [6], left {294, 999997})

and it never ends (endless cycle)? So what does SELECT() means in strace output? Where could be the problem?

thanks, Dmitry

share|improve this question
    
select() is a system call similar to poll(). It checks the state on a file descriptor. A complete strace output (via gist/pastebin) would be helpful in investigating this further. You can invoke vpnc with strace from the command line. –  Tommy Sep 27 '12 at 7:32
    
Hi Tommy, thanks for your answer. If I run strace on vpnc when it takes 100% CPU - I get thousands of SELECT statements above. So did you say that I should run vpnc with strace from beginning and then wait until SELECT () statement start to appear? And then post it here? –  DmitrySemenov Sep 27 '12 at 18:16
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