On May 27, 2014, at 9:14 AM, Sudheer Vinukonda <sudhe...@yahoo-inc.com> wrote:
> > > On 5/27/14, 8:47 AM, "James Peach" <jpe...@apache.org> wrote: > >> On May 27, 2014, at 7:33 AM, Sudheer Vinukonda <sudhe...@yahoo-inc.com> >> wrote: >> >>> >>> >>> On 5/26/14, 6:00 PM, "James Peach" <jpe...@apache.org> wrote: >>> >>>> Bryan, >>>> >>>> How are you expecting proxy.process.ssl.total_handshake_time to be >>>> used? >>>> What units is it in? Unless I'm missing something, the aggregate >>>> handshake time does not seem very interesting. >>> >>> >>> From what I can see in the patch, >>> proxy.process.ssl.total_handshake_time = >>> proxy.process.ssl.total_*successful*_handshake_time and this is likely >>> meant to be used with proxy.process.ssl.total_success_handshake_count, >>> to >>> determine the average *successful* handshake duration. This should be >>> useful in measuring the ssl handshake latency and perhaps how much >>> improvement is seen with features such as ssl session reuse or spdy. >> >> This is a very shaky rationale for this metric and a very limited use >> case. If you want to measure SSL handshake time, then you should measure >> it directly. >> >> If you try to measure it with this metric, you will need to use the >> connection_count metrics, which are also of dubious general utility since >> they are counters, not gauges. Even when you do that, all you can do is >> measure the average, which is not very interesting. You really want to >> measure the average and the variance, or even generate a heat map. To do >> this, you need per-request values. >> >> I think that you should nuke this metric and write a plugin to gather the >> data you actually need. Use or extend the transaction milestone API to >> get the session accept timestamp. You can use the kernel TCP info socket >> option to measure round trips, estimated latency, etc. > > We have post processing tools that collect this metric pretty regularly > and should be able to give the variance/average etc. Yes, we do plan to > extend the transaction milestone API to get the session accept timestamp. How can you get variance of a total? J
