Query about keepalive

[Fasih]

Thanks a lot for the response.


> Just a side note: you may want to avoid setting keepalive bigger
> than your backend is able to handle, keeping in mind that it's
> not a hard limit on connections established, but rather size of
> connection cache kept by each worker.

I didnt realize that. I did run the test with keepalive 16 but the
results are similiar.


> Just a side note: please do not use html to post here.  We'll
> won't see it anyway, and plain text of your message is somewhat
> unreadable.


Sorry about that. Wiki format:
 || Session || Keepalive || Conns upstream || Conn Time || Unique
upstream hosts || Reqs upstream || Avg time to 1st byte || Max
upstream conn reuse || Client conns(1) || Client reqs(1) || Client
replies(1) || Testdur(1) || Client conns || Client reqs || Client
replies || Testdur ||
| site | 1 | 48 | 8.30858 | 19 | 192 | 0.152623 | 31 | 2 | 130 | 130 |
31.219 | 8 | 520 | 520 | 78.064 |
| site | 0 | 192 | 20.7169 | 19 | 192 | 0.167946 | 1 | 2 | 130 | 130 |
25.680 | 8 | 520 | 520 | 71.781 |

> How many times did you run the test?  From numbers it looks like
> you are measuring your network and/or upstream server performance,
> and I suspect this might fluctuate widely.  You might want to do
> the test at least 3 times in each configuration to be able to see
> the difference between two configurations.
>
I repeated this for quite a number of times, the trend is, the
increased number of upstreams (ie. I configure a.mysite,
images.mysites... etc) the slower it gets.

>
> If the difference will still be there, you may want to share more
> details about your setup (provide nginx configs, network details,
> description of the upstream servers involved, probably debug log
> for a deeper investigation).

configuration consists of some 20s of these(0-20):
  server {
      server_name 0.my-site.com;
      listen 10010;
      location / {
        proxy_pass http://0.my-site.com;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        proxy_cache my-cache;
      }
    }

And other than these I dont think I modified any setting
    server_names_hash_max_size 1024;
    proxy_cache_path  /tmp/cache levels=1:2 keys_zone=my-cache:8m
max_size=1000m inactive=600m;

>
> It is possible that keepalive connections to upstreams will lead
> to worse overall performance than no keepalives (notably due to
> various network effects and upstream servers behaviour), but I
> wouldn't expect it to be slower in general.

If you can give pointers as to what to look for, I could investigate more.
The logs generated are huge for a moderate load, not sure if attaching
is a good idea. I can grep out keepalive|upstream if you want

Thanks again for your patience and time