Stream: t-compiler/rust-analyzer

Topic: enable proc-macro and build-script in metrics


Edwin Cheng (Apr 06 2021 at 09:51, on Zulip):

I would like to enable proc-macro and build-script in metrics to match the default settings of RA.

Good idea or not ?

Laurențiu (Apr 06 2021 at 09:52, on Zulip):

I'm worried about practically losing the historical measurements

matklad (Apr 06 2021 at 10:07, on Zulip):

I think loosing historical data is fine. We are mostly interested in last week perf, not in the long-term trends.

matklad (Apr 06 2021 at 10:07, on Zulip):

We can always recrated historical data by going back in the git's history.

matklad (Apr 06 2021 at 10:13, on Zulip):

:thinking:

I now realize that, in general, if you want to observe historical perf trends, collecting a history of measurements in time is wrong, and instead it's more robust to re-create historical data. That way, you are protected from configuration changes (GitHub actions upgrading VMs)

Laurențiu (Apr 06 2021 at 10:15, on Zulip):

Of course, if you have your own hardware infra it's easier to keep it more consistent. I noticed that GHA has at least two different CPU types.

Laurențiu (Apr 06 2021 at 10:17, on Zulip):
$ git log --merges --oneline | wc -l
5042

That's gonna take a while.

matklad (Apr 06 2021 at 10:19, on Zulip):

@Laurențiu that depends on how much history you want. Fun fact: the timing infrastructure in IntelliJ reports times in wall-clock machine independent format. That is, the measure is milliseconds, but they are multiplied by the "scaling factor": how much the current CPU is faster than a canonical CPU

matklad (Apr 06 2021 at 10:19, on Zulip):

Canonical CPU is Pentium 4

matklad (Apr 06 2021 at 10:20, on Zulip):

That's gonna take a while.

You probably don't want to sample the history linearly, and insterad want something more exponential, line 2, 4, 8, 16, 32, 64, 128, 256 commits back

matklad (Apr 06 2021 at 10:20, on Zulip):

or some kind of adaptive sampling.

Laurențiu (Apr 06 2021 at 10:21, on Zulip):

And it's still slow :laughter_tears: (sorry for the jab, somehow I never managed to like IntelliJ). But yeah, it's a sensible approach; I imagine it can have problems when you start adding and using more cores, Amdahl's law and all that.

Last update: Jul 26 2021 at 13:30UTC