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[lvs-users] problems with ipvsadm - 3 seconds delay

To: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: [lvs-users] problems with ipvsadm - 3 seconds delay
From: Rai <luis.reina@xxxxxxxxxxxxxx>
Date: Thu, 28 Feb 2008 17:02:02 +0100
I'm running a load balancer with ipvsadm with 10 lighttpd servers.
Serving more than 6 million pages per day.

Sometimes i have 3 (or 9) seconds of delay load balancer is serving pages.

If i request a page directly to the lighttpd server, i haven't any problem.

but if i request using load balancer sometimes i have exactly 3 seconds
of delay

example:

Direct request to a server:
_________________________________________________________
ab -n10000 -c100 192.168.20.147/img/logo.gif

Document Path:          /img/logo.gif
Document Length:        3303 bytes

Concurrency Level:      100
Time taken for tests:   0.43075 seconds
Complete requests:      1000
Failed requests:        0
Write errors:           0
Total transferred:      3590486 bytes
HTML transferred:       3362454 bytes
Requests per second:    23215.32 [#/sec] (mean)
Time per request:       4.307 [ms] (mean)
Time per request:       0.043 [ms] (mean, across all concurrent requests)
Transfer rate:          81392.92 [Kbytes/sec] received

Connection Times (ms)
               min  mean[+/-sd] median   max
Connect:        0    1   0.2      1       2
Processing:     1    2   1.0      3       7
Waiting:        0    1   0.6      1       5
Total:          2    3   1.0      4       8
WARNING: The median and mean for the processing time are not within a
normal deviation
         These results are probably not that reliable.
WARNING: The median and mean for the total time are not within a normal
deviation
         These results are probably not that reliable.

Percentage of the requests served within a certain time (ms)
   50%      4
   66%      4
   75%      4
   80%      4
   90%      4
   95%      4
   98%      5
   99%      7
  100%      8 (longest request)
_________________________________________________________

Using load balancer:

http://x.x.x.x:3147/img/logo.gif
Percentage of the requests served within a certain time (ms)
   50%      4
   66%      4
   75%      4
   80%      4
   90%      4
   95%      7
   98%      3025
   99%      3017
  100%      3038 (longest request)


_________________________________________________________

Using debian etch 2.6.19 with default configuration of kernel.

Any idea?


Best regards





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