Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:121050
MIME-Version: 1.0
References: <e6d0f349-436d-8545-4146-e1293c901d65@bastelstu.be>
 <CAAwdEzD=3cG17jCz8v4dT1qoCMOjxEgqh1UvSwk-MU2nVEMA2A@mail.gmail.com>
 <076e8c8a-9f17-0163-acad-87df7f4302a1@bastelstu.be> <CAJmy8YGW6PTuVvUijHQ4jBHnd-jtHMg8EtuuASR=VP5gmQjo1g@mail.gmail.com>
 <7da23206-9cd9-947d-fa19-645ae21923cb@bastelstu.be>
In-Reply-To: <7da23206-9cd9-947d-fa19-645ae21923cb@bastelstu.be>
Date: Tue, 12 Sep 2023 23:35:56 +0200
Message-ID: <CAJmy8YFe-bD+zeCaps9hvVijWS=Z6UNpAGapO_P1OouoLh31pQ@mail.gmail.com>
To: =?UTF-8?Q?Tim_D=C3=BCsterhus?= <tim@bastelstu.be>
Cc: PHP internals <internals@lists.php.net>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Subject: Re: [PHP-DEV] RFC: Increasing the default BCrypt cost
From: divinity76@gmail.com (Hans Henrik Bergan)

>you're also measuring the startup cost of PHP itself.

yup correct

>A simple microtime(true) benchmark loop as used with my test script should=
 be fine for ballpark estimates

agreed

>dwarfing the measurement overhead.

wouldn't count out random cpu context switch/background noise
completely, see my hyperfine benchmark for cost 13:
>  Range (min =E2=80=A6 max):   717.3 ms =E2=80=A6 754.5 ms    10 runs
- over 10 runs, the fastest was 717ms and the slowest was 754ms, so
background noise made at least 37ms difference there.. but yeah
anyway, here's from your script:

hanshenrik@jonathan-dayton:~$ time php bench.php
Cost 8: 2.022854 total (0.020229 per hash)
Cost 9: 4.176210 total (0.041762 per hash)
Cost 10: 8.121596 total (0.081216 per hash)
Cost 11: 16.919405 total (0.169194 per hash)
Cost 12: 33.059071 total (0.330591 per hash)
Cost 13: 66.761731 total (0.667617 per hash)
Cost 14: 140.695820 total (1.406958 per hash)

real    4m31.854s
user    4m13.115s
sys     0m2.168s
hanshenrik@jonathan-dayton:~$ cat /proc/cpuinfo | head
(...)
model name      : AMD Opteron(tm) Processor 4122

On Tue, 12 Sept 2023 at 18:01, Tim D=C3=BCsterhus <tim@bastelstu.be> wrote:
>
> Hi
>
> On 9/12/23 17:56, Hans Henrik Bergan wrote:
> >> web hosters *love* their ancient hardware
> >
> > No kidding. dreamhost.com host over 1.5 million websites, presumably mo=
st
> > are on their "Shared Unlimited" package, which runs on
> > AMD Opteron 4122, a high-end server CPU from 2010.
> > Some benchmarks there:
>
> It appears your benchmarks are broken, because you're also measuring the
> startup cost of PHP itself. You should see an approximate doubling in
> time taken for each increase of the cost, but you have 122ms for 9 and
> 166ms for 10.
>
> A simple microtime(true) benchmark loop as used with my test script
> should be fine for ballpark estimates, as password_hash() is pretty
> heavy, dwarfing the measurement overhead.
>
> Best regards
> Tim D=C3=BCsterhus