#small #vec #vector #stack #tuning


Wrapper for SmallVec that writes out capacity information

1 unstable release

Uses old Rust 2015

0.0.1 Sep 13, 2018

#12 in #tuning


434 lines

Tune your SmallVecs!

This is a Work In Progress. Issues and Pull Requests Welcome!

You can use this crate to get information on how your code uses SmallVecs. What it does is writing a log of all SmallVec constructions, resizings and destructions by array size.

Each line in the log is composed of <item size>;<array size>;[+/-];<capacity>, where the first item is the size of the array's item type, the second is the array size (we can use this to distinguish various smallvec uses within one application), the third is + for a new allocation and - for a deallocation and the fourth is the resulting capacity.

For example, creating a smallvec of u8, extending and dropping it may create the following log (here annotated for clarity):

1;1;+;1       # create
1;1;+;100     # extend (allocate+deallocate)
1;1;-;100     # drop



In your Cargo.toml, replace your smallvec dependency with smallvectune. Then you need to use smallvectune::SmallVec istead of smallvec::SmallVec. It's also a good idea to call let _log = smallvectune::with_log() in your main method, otherwise some entries may be lost.

Calling your code, you'll have to set the SMALLVECTUNE_OUT environment variable to a valid path to write to. This is where the log will be written.


This is under Apache/2 or MIT license, per your choice. All contributions are also given under the same license.


~29K SLoC