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From James Peach <jpe...@apache.org>
Subject Re: iowait
Date Tue, 12 Jul 2016 23:00:02 GMT

> On Jul 12, 2016, at 6:05 AM, Randeep <randeep123@gmail.com> wrote:
> 
> Hi all,
> 
> I'm trying to understand what is causing the load on the ats server. Not sure whether
is RAM or disk or CPU is giving the issues.

From the output you posted it seems pretty likely that you are IO bound on reads. You should
investigate why that is happening. For most caching workloads, I would expect the RAM cache
to give a good hit rate, so that is one avenue of investigation.

> on top output I can see a lot of iowait.
> 
> top - 18:12:00 up  4:32,  3 users,  load average: 8.15, 8.20, 8.53
> Tasks: 234 total,   2 running, 232 sleeping,   0 stopped,   0 zombie
> Cpu(s):  7.2%us, 10.7%sy,  0.0%ni, 34.0%id, 46.5%wa,  0.0%hi,  1.7%si,  0.0%st
> Mem:   7848208k total,  7701228k used,   146980k free,    20008k buffers
> Swap:  8388604k total,   426796k used,  7961808k free,   250532k cached
> 
>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
> 14138 ats       20   0 8199m 6.7g 4852 S  9.0 89.8   7:23.41 /opt/ats/bin/traffic_server
-M --bind_stdout /opt/ats/var/log/trafficserver/traffic.out --bind_stderr /opt/
> 
> And on iostat,
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz avgqu-sz 
 await  svctm  %util
> sda               0.00    83.00  257.00   54.00 134672.00 21248.00   501.35    10.51
  33.69   3.22 100.00
> 
> on iotop:
> Total DISK READ: 50.46 M/s | Total DISK WRITE: 14.35 M/s
>   TID  PRIO  USER     DISK READ  DISK WRITE  SWAPIN     IO>    COMMAND
> 14154 be/4 ats         3.33 M/s    0.00 B/s  0.00 % 91.45 % traffic_server -M --bind_stdout
/opt/ats/var/log/traf~s/var/log/trafficserver/traffic.out --httpport 80:fd=9
> 14156 be/4 ats         7.28 M/s 2025.05 K/s  0.00 % 90.56 % traffic_server -M --bind_stdout
/opt/ats/var/log/traf~s/var/log/trafficserver/traffic.out --httpport 80:fd=9
> 14157 be/4 ats         6.88 M/s    0.00 B/s  0.00 % 90.52 % traffic_server -M --bind_stdout
/opt/ats/var/log/traf~s/var/log/trafficserver/traffic.out --httpport 80:fd=9
> 14155 be/4 ats         2.53 M/s    3.32 M/s  0.00 % 82.89 % traffic_server -M --bind_stdout
/opt/ats/var/log/traf~s/var/log/trafficserver/traffic.out --httpport 80:fd=9
> 14158 be/4 ats         9.58 M/s    3.33 M/s  0.00 % 75.91 % traffic_server -M --bind_stdout
/opt/ats/var/log/traf~s/var/log/trafficserver/traffic.out --httpport 80:fd=9
> 14161 be/4 ats         7.67 M/s    0.00 B/s  0.00 % 73.36 % traffic_server -M --bind_stdout
/opt/ats/var/log/traf~s/var/log/trafficserver/traffic.out --httpport 80:fd=9
> 14159 be/4 ats         5.89 M/s 2025.05 K/s  0.00 % 73.27 % traffic_server -M --bind_stdout
/opt/ats/var/log/traf~s/var/log/trafficserver/traffic.out --httpport 80:fd=9
> 14160 be/4 ats         7.30 M/s    3.75 M/s  0.00 % 66.01 % traffic_server -M --bind_stdout
/opt/ats/var/log/traf~s/var/log/trafficserver/traffic.out --httpport 80:fd=9
> 
> But I have disabled all the logs. I don't know why it still shows. On production, usually
everyone disables the logs?
> 
> [root@main ~]# free -m
>              total       used       free     shared    buffers     cached
> Mem:          7664       7488        175          0         13        210
> -/+ buffers/cache:       7265        398
> Swap:         8191        416       7775
> [root@main ~]# w
>  18:15:25 up  4:35,  3 users,  load average: 8.07, 8.14, 8.43
> 
> I am using ats to cache live channels. Currently I have enabled 45 channels. We have
to enable 400 channels. So I am checking what resources I have to add.
> 
> Any suggestions will be appreciated
> 
> Best Regards,
> -- 
> Randeep
> Mob: +919447831699[kerala]
> Mob: +919880050349[B'lore]
> http://twitter.com/Randeeppr
> http://in.linkedin.com/in/randeeppr
>  
> 
>  	
> Randeep Raman
> about.me/Randeeppr
>  				
>  


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