Seems like the time has come to replace our home-grown profiling infra with tracing: https://github.com/rust-lang/rust/pull/74726
:eyes: but also ouch on that perf report :sweat:
oh goodness, that's one hell of a perf report
is the compile-time max_log_level thingy not working?
I think this might be the issue: https://github.com/rust-lang/rust/pull/74726#discussion_r460553066
I was able to reproduce that on my computer
(no playground link, unfortunately. tracing's not in there yet)
Eliza commented with more details: https://github.com/rust-lang/rust/pull/74726#discussion_r460557136
Another update: after resolving the issues rustc encountered, the perf results indicated that tracing's within 10% of
log when enabled (day-to-day rustc users won't see this). this regression occurs due to the initial callsite registration relatively slow (a few dozen milliseconds), but since tracing was highly optimized around long-lived network applications, this initial registration was almost completely amortized and invisible to most of
tracing's users. Eliza gave some additional details: https://github.com/rust-lang/rust/pull/74726#issuecomment-664482501
there should be a fix for this Soon, perhaps in the next day or so.