stream: improve read() performance

[mscdex]

Result:

                                                        confidence improvement accuracy (*)   (**)   (***)
 streams/readable-readall.js n=5000                           ***     85.06 %       ±2.87% ±3.84%  ±5.05%

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/24843/

[ronag]

@mscdex Sorry to ask here. But, how do I generate/run that benchmark?

[mscdex]

@ronag

Locally:

$ node benchmark/compare.js --new ./node --old ./node-master --filter readable-readall -- streams | Rscript benchmark/compare.R

or run it in benchmark CI and fill out some of the same parameters.

[Trott]

@ronag After running the benchmark as @mscdex describes, you'll want to process the results via compare.R to get the output similar to what @mscdex has in the PR here and probably what you've seen elsewhere in the issue tracker. Further details about benchmarks and the associated scripts are in https://github.com/nodejs/node/blob/master/doc/guides/writing-and-running-benchmarks.md, especially https://github.com/nodejs/node/blob/master/doc/guides/writing-and-running-benchmarks.md#comparing-nodejs-versions.

[Trott]

Oops, I see @mscdex included the R script at the end, so ignore that part of what I wrote. But the guide link may still come in handy.

[Trott]

Landed in 0b5b81c