Re: [PATCH v2 4/4] Bump rename limit defaults (yet again)

From: Jeff King <peff@peff.net>
To: Elijah Newren <newren@gmail.com>
Cc: "Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com>,
	"Git Mailing List" <git@vger.kernel.org>,
	"Bagas Sanjaya" <bagasdotme@gmail.com>,
	"Eric Sunshine" <sunshine@sunshineco.com>,
	"Derrick Stolee" <stolee@gmail.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: Re: [PATCH v2 4/4] Bump rename limit defaults (yet again)
Date: Wed, 14 Jul 2021 16:47:00 -0400	[thread overview]
Message-ID: <YO9NROIgMpo2zqU/@coredump.intra.peff.net> (raw)
In-Reply-To: <CABPp-BE=Ghkm=sZ05=A=1vC1zscbVk7qXgeEjpA5gHxsfTGAyg@mail.gmail.com>

On Wed, Jul 14, 2021 at 01:03:43PM -0700, Elijah Newren wrote:

> > The 2008 timings are from the old email you linked in your commit
> > message, and the new one is from running the revised script you showed.
> > The savings seem like more than 30%. I don't know if that's all CPU or
> > if something changed in the code.
> 
> I was using the script you wrote in 2008, but comparing to your
> reported numbers in 2011[1].  When you bumped in 2011, you said you
> picked the limits of 400 & 1000 in order to give rough timings of 2s
> and 10s.  So the table looks more like:
> 
>    N  CPU (2008)  CPU (2011)  c5xlarge  CPU (yours)
>  400    4.87s         ~2s      1.106s      0.788s
> 1000   27.82s        ~10s      6.350s      4.431s
> 
> So, 2011->c5xlarge on these (just recomputed now numbers) show
> improvements of ~45% and ~36%.  Maybe I had an outlier run earlier
> that was in the upper 6s range for N=1000 and I rounded off to 30% for
> the commit message?  Don't know, those numbers are on a laptop that
> died in the last few days.

Ah, right. I forgot about the 2011 update. So yeah, things are getting
faster, but not as much as I would have hoped as somebody who came of
age during the clock speed boom of the 90's. :)

Thanks for humoring my puzzlement (I don't think any of this changes the
applicability of your patch).

-Peff