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From:   Alexander Potapenko <glider@google.com>
Date:   Tue, 10 Oct 2023 14:14:52 +0200
Message-ID: <CAG_fn=VnTiPVpofPQKmGiAvzHOCb7weYO_pmyexQ-7+xn8_ukw@mail.gmail.com>
Subject: Re: [PATCH v6 1/5] lib/bitmap: add bitmap_{read,write}()
To:     Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc:     Yury Norov <yury.norov@gmail.com>, catalin.marinas@arm.com,
        will@kernel.org, pcc@google.com, andreyknvl@gmail.com,
        andriy.shevchenko@linux.intel.com, aleksander.lobakin@intel.com,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        eugenis@google.com, syednwaris@gmail.com, william.gray@linaro.org,
        Arnd Bergmann <arnd@arndb.de>
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On Tue, Oct 10, 2023 at 1:03=E2=80=AFPM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
>
> On 10/10/2023 11.17, Alexander Potapenko wrote:
>
> >> 'behaves similarly' sounds like an understatement. I think, it behaves
> >> much faster because it can assign up to 64 bits at once, not mentionin=
g
> >> the pressure on cache lines traffic.
> >
> > My intent was to describe the visible behavior, of course the
> > generated code is better, and the number of memory accesses lower.
> >
> > How about the following description:
> >
> >  * The result of bitmap_write() is similar to @nbits calls of assign_bi=
t(), i.e.
> >  * bits beyond @nbits are ignored:
> >  *
> >  *   for (bit =3D 0; bit < nbits; bit++)
> >  *           assign_bit(start + bit, bitmap, val & BIT(bit));
> >
> > ?
>
> C programmers should know the meaning of the term "as-if". Perhaps use
> that. Smth like "bitmap_write() behaves as-if implemented as @nbits
> calls of __assign_bit()".

Good idea, I'll go with this one.
Thank you!