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Message-ID: <CAMuHMdVpKk=EPsAQDb_6kJ08kKx6SF6RvuTZHQLDHHWrJYQJRg@mail.gmail.com> Date: Tue, 21 Nov 2017 09:38:27 +0100 From: Geert Uytterhoeven <geert@...ux-m68k.org> To: Yury Norov <ynorov@...iumnetworks.com> Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Alexey Dobriyan <adobriyan@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, Clement Courbet <courbet@...gle.com>, Matthew Wilcox <mawilcox@...rosoft.com>, Rasmus Villemoes <linux@...musvillemoes.dk> Subject: Re: [PATCH] lib: test module for find_*_bit() functions Hi Yury, On Thu, Nov 9, 2017 at 3:07 PM, Yury Norov <ynorov@...iumnetworks.com> wrote: > find_bit functions are widely used in the kernel, including hot paths. > This module tests performance of that functions in 2 typical scenarios: > randomly filled bitmap with relatively equal distribution of set and > cleared bits, and sparse bitmap which has 1 set bit for 500 cleared bits. Thanks for your patch! > On ThunderX machine: > > Start testing find_bit() with random-filled bitmap > [1032111.632383] find_next_bit: 240043 cycles, 164062 iterations > [1032111.647236] find_next_zero_bit: 312848 cycles, 163619 iterations > [1032111.661585] find_last_bit: 193748 cycles, 164062 iterations > [1032113.450517] find_first_bit: 177720874 cycles, 164062 iterations > [1032113.462930] > Start testing find_bit() with sparse bitmap > [1032113.477229] find_next_bit: 3633 cycles, 656 iterations > [1032113.494281] find_next_zero_bit: 620399 cycles, 327025 iterations > [1032113.506723] find_last_bit: 3038 cycles, 656 iterations > [1032113.524485] find_first_bit: 691407 cycles, 656 iterations That's what ends up in dmesg, but that's not what it prints on the console: "\t" prints an ugly placeholder, as TABs are not supported. > --- /dev/null > +++ b/lib/test_find_bit.c > @@ -0,0 +1,141 @@ > +static int __init test_find_first_bit(void *bitmap, unsigned long len) > +{ > + unsigned long i, cnt; > + cycles_t cycles; > + > + cycles = get_cycles(); get_cycles() returns zero on half of the architectures. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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