Re: A potential approach to making tests faster on Windows

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Apr 3, 2018, 15:55 UTC
Message-ID: <nycvar.QRO.7.76.6.1804031749080.5026@qfpub.tvgsbejvaqbjf.bet>
In-Reply-To: <87sh8cv8a5.fsf@evledraar.gmail.com>

Hi Ævar,

On Tue, 3 Apr 2018, Ævar Arnfjörð Bjarmason wrote:

> [...] I think it would be really interesting to see the third
> approach I suggested, i.e. hack the shell to make the test_cmp a builtin
> and test that. Then you won't fork, but will get the advantage of your
> fast C codepath.

That should be relatively equivalent to running in BusyBox-w32's ash. BusyBox-w32 is a pure-Win32 version of BusyBox (i.e. it does not use any POSIX emulation layer, not Cygwin nor MSYS2).

I did not notice any Earth-shaking performance improvement when running a test with BusyBox-w32's ash. It was a couple of percent, maybe even 20% faster, but nowhere near the orders of magnitude I had been expecting.

Show 5 quoted lines

> Also, even if test_cmp is much faster, Peff's results over at
> https://public-inbox.org/git/20161020123111.qnbsainul2g54z4z@sigill.intra.peff.net/
> suggest that you may not notice anyway. Aside from the points raised
> there about the bin wrappers it seems the easiest wins are having a
> builtin version of "rm" and "cat".

In BusyBox-w32, `rm` and `cat` *are* built-ins.

> Are you able to compile dash on Windows with some modification of the
> patch I sent upthread?

In theory, yes. In practice, I lack the time (and I do not expect this to have any performance benefit over using BusyBox-w32 to run the test suite).

Ciao, Dscho