Currently we still see some flakes on perf dashboard (e.g. sys-stack is quite frequent).
I am planning to run real perf builder with 5 different values of GOMAXPROCS,
so we can require 3 builders to agree on a change instead of 2.
This will provide 20x improvement in flake detection.
At the same time lower noise bar from 1.2 to 1.1, as I see some real perf changes gets ignored as noise.
All these magic numbers affect only representation of data, but not the data stored in DB.
So we can continue freely tuning them later. There are no significant risks here.
LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/127520044
This CL moves code from code.google.com/p/dvyukov-go-perf-dashboard,
which was previously reviewed.
UI part will be submitted separately.
LGTM=adg
R=adg
CC=golang-codereviews
https://golang.org/cl/97260043
