Hi Bryan,
On Thu, Oct 26, 2017 at 03:51:33PM -0700, Bryan Talbot wrote:
> > 4. Local haproxy log
> > 172.31.x.x:53202 [26/Oct/2017:21:02:36.368] http_front http_back/web1
> > 0/0/204/205/410 200 89 - - ---- 0/0/0/0/0 0/0 {} "GET / HTTP/1.0"
>
>
> This log line says that it took your local proxy 204 ms to connect to the
> remote proxy and that the first response bytes from the remote proxy were
> received by the local proxy 205 ms later for a total round trip time of 410
> ms (after rounding).
>
> The only way to get the total time to be equal to the network latency times
> would be to make the remote respond in 0 ms (or less!). If the two proxies
> are actually 200 ms apart, I don't see how you could do much better.
Not exactly in fact, what Karthikeyan is observing totally makes sense.
The first round trip is used for the SYN->SYN/ACK, the second one for
request->response. The server roughly takes 2 ms to respond if the ping
is 204ms and the total time is 410ms (410-2*204).
Regarding http-reuse, it indeed only reuses idle connections, and there
are certain conditions for this. The first one obviously is that the
response must be made in keep-alive so that the connection is kept open.
If "ab" is used to inject, it needs "-k" to enable keep-alive otherwise
by default a close is requested and the connections are closed. I'm
suddenly wondering if using "option http-pretend-keepalive" could help
cheating here, I honnestly don't know.
Willy
