Re: [RFC] fbdev/riva:change to use generice function to implement reverse_order()

From	Afzal Mohammed <afzal.mohd.ma@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [RFC] fbdev/riva:change to use generice function to implement reverse_order()
Date	2015-08-24 15:50 +0200
Message-ID	<q10im-T2-21@gated-at.bofh.it> (permalink)
References	(3 earlier) <pZOjf-4fE-1@gated-at.bofh.it> <pZPfj-5Az-3@gated-at.bofh.it> <pZPyH-6cu-23@gated-at.bofh.it> <q0bSy-4j2-11@gated-at.bofh.it> <q0Vsl-2pv-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Hi,

On Mon, Aug 24, 2015 at 04:31:13PM +0800, yalin wang wrote:
> 
> i only submit the bit reverse patch for arm / arm64 arch,

yes, saw later git blaming it on you :)

> > Not for this case, but once measured on ARM, iirc, a 32-bit asm bit
> > reversal as compared to doing it in C was taking 1 cycle as opposed to
> > ~225 cycles!, of course writing optimized C could have made it fare
> > better, but still would reach no-way near asm bit reversal.

The above measurement was done not in Linux, rather on a baremetal
code, but seeing the efficient Kernel C implementation, realized that
the gain would not be that much, it would be good to know if there are
measurements for Kernel bitreversal in C & asm (on supported arch)

Regards
afzal
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Re: [RFC] fbdev/riva:change to use generice function to implement   reverse_order() Tomi Valkeinen <tomi.valkeinen@ti.com> - 2015-08-20 13:10 +0200
  Re: [RFC] fbdev/riva:change to use generice function to implement reverse_order() yalin wang <yalin.wang2010@gmail.com> - 2015-08-20 13:40 +0200
    Re: [RFC] fbdev/riva:change to use generice function to implement  reverse_order() Tomi Valkeinen <tomi.valkeinen@ti.com> - 2015-08-21 08:50 +0200
      Re: [RFC] fbdev/riva:change to use generice function to implement reverse_order() yalin wang <yalin.wang2010@gmail.com> - 2015-08-21 09:50 +0200
        Re: [RFC] fbdev/riva:change to use generice function to implement  reverse_order() Tomi Valkeinen <tomi.valkeinen@ti.com> - 2015-08-21 10:10 +0200
          Re: [RFC] fbdev/riva:change to use generice function to implement  reverse_order() Afzal Mohammed <afzal.mohd.ma@gmail.com> - 2015-08-22 10:00 +0200
            Re: [RFC] fbdev/riva:change to use generice function to implement reverse_order() yalin wang <yalin.wang2010@gmail.com> - 2015-08-24 10:40 +0200
              Re: [RFC] fbdev/riva:change to use generice function to implement  reverse_order() Afzal Mohammed <afzal.mohd.ma@gmail.com> - 2015-08-24 15:50 +0200

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