580447 - Add a "file" function in the js shell

Status: RESOLVED INVALID

(Core :: JavaScript Engine, defect)

Description

[Paul Biggar]

Attachment: Adds "file" to JS shell

`file` reads the contents of a file to a JS string.

The problem this solves is that reading from disk on linux is noisy (2-3%), and its making it difficult to tell if patches have any effect on the benchmark run-time. File allows separating reading from disk with evaling the code.

The patch isn't ready for landing (see call to fread), but it's good enough to test this.

Comment 1

[Sean Stangl [:sstangl]]

Benchmarks solve this problem by running a preliminary, unrecorded test to "pretty much ensure" that the requisite files are in cache for future runs. Is there any benchmark you specifically have in mind that requires re-reading from disk?

Alternate idea: create a RAMdisk; run benchmarks from there.

Comment 2

[Brendan Eich [:brendan]]

We already have snarf, no need for another workalike.

/be

Comment 3

[Paul Biggar]

(In reply to comment #2)
> We already have snarf, no need for another workalike.

Indeedy, I missed that.


(In reply to comment #1)
> Benchmarks solve this problem by running a preliminary, unrecorded test to
> "pretty much ensure" that the requisite files are in cache for future runs. Is
> there any benchmark you specifically have in mind that requires re-reading from
> disk?

No, I'm just getting very noisy benchmark results; sayre suggested disk io has an effect on linux.

> Alternate idea: create a RAMdisk; run benchmarks from there.

Great idea, will try that.

Comment 4

[Paul Biggar]

See bug 580532 for more attempts to reduce variability.