Reflow perf chapter

Author: jieyouxu

src/tests/perf.md

@@ -4,14 +4,15 @@
 
 A lot of work is put into improving the performance of the compiler and
 preventing performance regressions.
+
 The [rustc-perf](https://github.com/rust-lang/rustc-perf) project provides
-several services for testing and tracking performance.
-It provides hosted infrastructure for running benchmarks as a service.
-At this time, only `x86_64-unknown-linux-gnu` builds are tracked.
+several services for testing and tracking performance. It provides hosted
+infrastructure for running benchmarks as a service. At this time, only
+`x86_64-unknown-linux-gnu` builds are tracked.
 
 A "perf run" is used to compare the performance of the compiler in different
-configurations for a large collection of popular crates.
-Different configurations include "fresh builds", builds with incremental compilation, etc.
+configurations for a large collection of popular crates. Different
+configurations include "fresh builds", builds with incremental compilation, etc.
 
 The result of a perf run is a comparison between two versions of the compiler
 (by their commit hashes).
@@ -24,30 +25,29 @@ Any changes are noted in a comment on the PR.
 
 ### Manual perf runs
 
-Additionally, performance tests can be ran before a PR is merged on an as-needed basis.
-You should request a perf run if your PR may affect performance, especially if
-it can affect performance adversely.
+Additionally, performance tests can be ran before a PR is merged on an as-needed
+basis. You should request a perf run if your PR may affect performance,
+especially if it can affect performance adversely.
 
 To evaluate the performance impact of a PR, write this comment on the PR:
 
 `@bors try @rust-timer queue`
 
-> **Note**: Only users authorized to do perf runs are allowed to post this comment.
-> Teams that are allowed to use it are tracked in the [Teams
-> repository](https://github.com/rust-lang/team) with the `perf = true` value
-> in the `[permissions]` section (and bors permissions are also required).
-> If you are not on one of those teams, feel free to ask for someone to post
-> it for you (either on Zulip or ask the assigned reviewer).
+> **Note**: Only users authorized to do perf runs are allowed to post this
+> comment. Teams that are allowed to use it are tracked in the [Teams
+> repository](https://github.com/rust-lang/team) with the `perf = true` value in
+> the `[permissions]` section (and bors permissions are also required). If you
+> are not on one of those teams, feel free to ask for someone to post it for you
+> (either on Zulip or ask the assigned reviewer).
 
-This will first tell bors to do a "try" build which do a full release build
-for `x86_64-unknown-linux-gnu`.
-After the build finishes, it will place it in the queue to run the performance
-suite against it.
-After the performance tests finish, the bot will post a comment on the PR with
-a summary and a link to a full report.
+This will first tell bors to do a "try" build which do a full release build for
+`x86_64-unknown-linux-gnu`. After the build finishes, it will place it in the
+queue to run the performance suite against it. After the performance tests
+finish, the bot will post a comment on the PR with a summary and a link to a
+full report.
 
-If you want to do a perf run for an already built artifact (e.g. for a previous try
-build that wasn't benchmarked yet), you can run this instead:
+If you want to do a perf run for an already built artifact (e.g. for a previous
+try build that wasn't benchmarked yet), you can run this instead:
 
 `@rust-timer build <commit-sha>`
 
@@ -56,5 +56,6 @@ You cannot benchmark the same artifact twice though.
 More information about the available perf bot commands can be found
 [here](https://perf.rust-lang.org/help.html). 
 
-More details about the benchmarking process itself are available in the [perf collector
+More details about the benchmarking process itself are available in the [perf
+collector
 documentation](https://github.com/rust-lang/rustc-perf/blob/master/collector/README.md).