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Date:      Thu, 23 Jul 2020 18:00:01 +0000
From:      Colin Percival <cperciva@tarsnap.com>
To:        Doug Moore <dougm@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   Please include benchmarks in commit messages (was Re: svn commit: r363450 - in head: share/man/man3 sys/sys)
Message-ID:  <010001737cd501a6-34cc6066-95c3-4724-a5f7-7cb00193e223-000000@email.amazonses.com>
In-Reply-To: <202007231716.06NHGLNF020979@repo.freebsd.org>
References:  <202007231716.06NHGLNF020979@repo.freebsd.org>

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[Picking this as an example of a general trend...]

On 2020-07-23 10:16, Doug Moore wrote:
>   [...]
>   Testing has shown that for the cases where red-black trees do worst,
>   wavl trees better balance leads to faster lookups, so that if lookups
>   outnumber insertions by a nontrivial amount, lookup time saved exceeds
>   the extra cost of balancing.

I'd like to request that commits like this include some benchmarks.  In the
review of these particular changes I see several microbenchmarks for a variety
of use cases; it could be helpful to future code spelunkers if these were
summarized in the commit message (e.g. "lookup-heavy microbenchmarks saw a
X% speedup while write-heavy microbenchmarks saw a Y% slowdown").  It would
also be nice to see a macrobenchmark (e.g. buildworld), even (and perhaps
*especially*) if the result is "no difference was observed".

Again, this is a general request -- this is just the latest in a long series
of commits I've seen by many people which have sounded like they could have
performance impacts but have not included any quantitative results.

-- 
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid



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