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From: George Spelvin <lkml@sdf.org>
To: geert@linux-m68k.org, lkml@sdf.org
Cc: akpm@linux-foundation.org, andriy.shevchenko@linux.intel.com,
	daniel.wagner@siemens.com, dchinner@redhat.com,
	don.mullis@gmail.com, linux-kernel@vger.kernel.org,
	linux@rasmusvillemoes.dk, st5pub@yandex.ru
Subject: Re: [PATCH 4/5] lib/list_sort: Simplify and remove MAX_LIST_LENGTH_BITS
Date: Fri, 15 Mar 2019 16:59:44 GMT	[thread overview]
Message-ID: <201903151659.x2FGxi3R012970@sdf.org> (raw)
In-Reply-To: <CAMuHMdVgmb8eZ7bD+jye8DG7cQRywvVmwo_XNJ00f198pDcwxQ@mail.gmail.com>

On Fri, 15 Mar 2019 at 13:57:05 +0100, Geert Uytterhoeven wrote:
> On Fri, Mar 15, 2019 at 11:23 AM George Spelvin <lkml@sdf.org> wrote:
>> On Fri, 15 Mar 2019 at 09:20:58 +0100, Geert Uytterhoeven wrote:
>>> On Fri, Mar 15, 2019 at 5:33 AM George Spelvin <lkml@sdf.org> wrote:
>>>> One question I should ask everyone: should "count" be 32 or 64 bits
>>>> on 64-bit machines?  That would let x86 save a few REX bytes.  (815
>>>> vs. 813 byte code, if anyone cares.)
>>>>
>>>> Allegedy ARM can save a few pJ by gating the high 32
>>>> bits of the ALU.
>>>>
>>>> Most other 64-bit processors would prefer 64-bit operations as
>>>> it saves masking operations.
> 
> So just make it unsigned int, unconditionally.

As I wrote originally (and quoted above), other 64-bit machines don't
have 32-bit operations and prefer 64-bit operations because they don't
require masking.  x86 (for historical compatibiity) and ARM (for power
saving) are the ones that come to mind.

I'm trying to present the case to spur discussion, but it realy is
a *question* I'm asking about whether to do that, not a suggestion
phrased as a question.

  reply	other threads:[~2019-03-15 17:00 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-09  2:17 [PATCH 0/5] lib/sort & lib/list_sort: faster and smaller George Spelvin
2019-02-21  6:30 ` [PATCH 1/5] lib/sort: Make swap functions more generic George Spelvin
     [not found]   ` <20190309140653.GO9224@smile.fi.intel.com>
2019-03-09 15:53     ` lkml
2019-03-09 20:19       ` Andrey Abramov
2019-03-14  9:29       ` Andy Shevchenko
2019-03-14 10:09         ` George Spelvin
2019-03-14 10:41           ` Geert Uytterhoeven
2019-03-14 11:53             ` George Spelvin
2019-03-14 12:18               ` Andy Shevchenko
2019-03-14 19:59                 ` Andrey Abramov
2019-03-15  3:35                   ` George Spelvin
2019-03-15  8:27                     ` Geert Uytterhoeven
2019-03-14 10:11         ` George Spelvin
2019-03-09 21:02     ` George Spelvin
2019-03-13 21:23   ` Rasmus Villemoes
2019-03-13 22:02     ` Geert Uytterhoeven
2019-03-13 23:15     ` George Spelvin
2019-02-21  8:21 ` [PATCH 2/5] lib/sort: Use more efficient bottom-up heapsort variant George Spelvin
2019-03-13 22:29   ` Rasmus Villemoes
2019-03-14  0:03     ` George Spelvin
2019-03-14  0:15       ` Rasmus Villemoes
2019-02-21  8:21 ` [PATCH 3/5] lib/sort: Avoid indirect calls to built-in swap George Spelvin
2019-03-05  3:06 ` [PATCH 4/5] lib/list_sort: Simplify and remove MAX_LIST_LENGTH_BITS George Spelvin
2019-03-10 21:54   ` Rasmus Villemoes
2019-03-10 22:29     ` George Spelvin
2019-03-14  9:10   ` Andy Shevchenko
2019-03-14  9:41     ` George Spelvin
2019-03-15  4:33     ` George Spelvin
2019-03-15  8:20       ` Geert Uytterhoeven
2019-03-15 10:23         ` George Spelvin
2019-03-15 12:57           ` Geert Uytterhoeven
2019-03-15 16:59             ` George Spelvin [this message]
2019-03-15 17:47               ` Geert Uytterhoeven
2019-03-15 18:53                 ` Andrey Abramov
2019-03-15 19:06                   ` Andy Shevchenko
2019-03-15 19:23                     ` Andrey Abramov
2019-03-15 19:56                       ` Andy Shevchenko
2019-03-16  3:49                         ` George Spelvin
2019-03-05  5:58 ` [PATCH 5/5] lib/list_sort: Optimize number of calls to comparison function George Spelvin
2019-03-13 23:28   ` Rasmus Villemoes
2019-03-14  1:58     ` George Spelvin
2019-06-21 23:12       ` Rasmus Villemoes
2019-12-08  8:01         ` George Spelvin
2019-03-15 19:54 ` [PATCH 0/5] lib/sort & lib/list_sort: faster and smaller Andrey Abramov

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