What you are looking for sounds pretty much like my Backtrack project
[1]. It's still under development, tho, but I have strong motivations
to move it forward in Q4/17. The goal of Backtrack is exactly what you
are looking for - find the right scheduling prioritization. It's said
we don't have something like that ready right now, for 57.
I already proposed some latest details on Backtrack to Marcus Stange and
Nicholas Nethercote to replace TaskTracer with it, will cc you on the
thread.
-hb-
[1] https://www.janbambas.cz/backtrack-meets-gecko-profiler/
On 8/9/17 2:42 AM, Kris Maglione wrote:
One of my biggest frustrations in profiling startup performance has
been the fact that exactly which code runs during before or after
first paint changes based on arbitrary timing factors. If I make a 5ms
improvement to one section of code, a 100ms chunk of code winds up
running after first paint rather than before. If I make a 5ms
improvement to another section of code, a 150ms chunk of code winds up
running *before* first paint rather than after. This also shows up in
the ts_paint timings on talos, where we have a fairly consistent
cluster of high times, a fairly consistent cluster of low times, and
very little in-between.
Presumably, if we're OK with these chunks *ever* running after first
paint, then they should always run after first paint. And vice versa.
I've made various attempts to get a handle on this, but never with
much success. The last time, I got as far as fixing the broken
TaskTracer build before I finally gave up trying to find a useful way
to analyze the data. What I'd really like is a handle on what tasks
are run, when, who schedule them (and when), and what code they run.
After that, I'd ideally like to find a way to run async tasks during
startup so that I'm guaranteed which parts run before first paint and
which run after.
Has anyone else made any progress on this front? Are there any other
tools that I'm overlooking? Is there a sensible path forward?
Thanks.
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