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Message-ID: <1b13d089da46f091d66bbc8f96b1d4da881e53d1.camel@trillion01.com>
Subject: Re: [PATCH 0/2] abstract napi tracking strategy
From: Olivier Langlois <olivier@trillion01.com>
To: Jens Axboe <axboe@kernel.dk>, Pavel Begunkov <asml.silence@gmail.com>, 
	io-uring@vger.kernel.org
Date: Thu, 15 Aug 2024 18:44:45 -0400
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On Thu, 2024-08-15 at 18:17 -0400, Olivier Langlois wrote:
>=20
> To my eyes, what is really important, it is that absolute best
> technical solution is choosen and the only way that this discussion
> can
> be done, it is with numbers. So I have created a small created a
> small
> benchmark program to compare a function pointer indirect call vs
> selecting a function in a 3 branches if/else if/else block. Here are
> the results:
>=20
> ----------------------------------------------------------
> Benchmark=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 Time=A0=A0=A0=A0=
=A0=A0=A0=A0=A0=A0=A0=A0 CPU=A0=A0 Iterations
> ----------------------------------------------------------
> BM_test_virtual=A0=A0=A0=A0=A0 0.628 ns=A0=A0=A0=A0=A0=A0=A0 0.627 ns=A0=
=A0=A0 930255515
> BM_test_ifElse=A0=A0=A0=A0=A0=A0=A0 1.59 ns=A0=A0=A0=A0=A0=A0=A0=A0 1.58 =
ns=A0=A0=A0 446805050
>=20
I have fixed my benchmark:

----------------------------------------------------------
Benchmark                Time             CPU   Iterations
----------------------------------------------------------
BM_test_virtual       2.57 ns         2.53 ns    277764970
BM_test_ifElse        1.58 ns         1.57 ns    445197861

code:
using Func_t =3D bool (*)();

bool testVirtual(Func_t ptr)
{
    return ptr();
}

void BM_test_virtual(benchmark::State &state)
{
    volatile Func_t ptr =3D &static_tracking_do_busy_loop;

    for (auto _ : state) {
        benchmark::DoNotOptimize(testVirtual(ptr));
    }
}