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Re: speed of unaligned accesses that cross page-boundaries

From Juha Nieminen <nospam@thanks.invalid>
Newsgroups comp.lang.c++
Subject Re: speed of unaligned accesses that cross page-boundaries
Date 2022-04-19 12:51 +0000
Organization Aioe.org NNTP Server
Message-ID <t3mb81$ndi$1@gioia.aioe.org> (permalink)
References <t17mqk$cj4$1@dont-email.me> <t1947l$1jv3$2@gioia.aioe.org> <t3leom$neh$1@dont-email.me>

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Bonita Montero <Bonita.Montero@gmail.com> wrote:
>> IIRC both Intel and AMD got rid of the unaligned access penalty
>> at some point (relatively recently). ...
> 
> No, for a long time. Unaligned accesses are quite common for
> I/O purposes. The only unaligned access that is inefficient
> is when you cross a page-boundary (almost twice the lantency).

AFAIK Intel got rid of the penalty with the Sandy Bridge architecture
(i5-2400, i5-2500, i7-2600, i7-2700, etc). While that was 11 years ago,
that's "relatively recently" considering Intel's entire history.

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speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-03-20 18:04 +0100
  Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-03-20 18:08 +0100
  Re: speed of unaligned accesses that cross page-boundaries scott@slp53.sl.home (Scott Lurndal) - 2022-03-20 18:12 +0000
    Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-03-20 19:36 +0100
  Re: speed of unaligned accesses that cross page-boundaries "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-03-20 16:13 -0700
    Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-03-21 06:58 +0100
    Re: speed of unaligned accesses that cross page-boundaries scott@slp53.sl.home (Scott Lurndal) - 2022-03-21 14:49 +0000
  Re: speed of unaligned accesses that cross page-boundaries Juha Nieminen <nospam@thanks.invalid> - 2022-03-21 05:59 +0000
    Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-03-21 08:56 +0100
    Re: speed of unaligned accesses that cross page-boundaries scott@slp53.sl.home (Scott Lurndal) - 2022-03-21 14:53 +0000
      Re: speed of unaligned accesses that cross page-boundaries scott@slp53.sl.home (Scott Lurndal) - 2022-03-21 16:59 +0000
    Re: speed of unaligned accesses that cross page-boundaries Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-04-18 20:59 -0700
    Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-04-19 06:45 +0200
      Re: speed of unaligned accesses that cross page-boundaries Juha Nieminen <nospam@thanks.invalid> - 2022-04-19 12:51 +0000
        Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-04-19 15:17 +0200
      Re: speed of unaligned accesses that cross page-boundaries scott@slp53.sl.home (Scott Lurndal) - 2022-04-19 14:11 +0000
        Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-04-19 16:15 +0200
          Re: speed of unaligned accesses that cross page-boundaries "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-04-27 01:52 -0700
            Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-04-27 20:02 +0200
            Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-04-28 08:19 +0200
              Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-04-28 12:19 +0200
                Re: speed of unaligned accesses that cross page-boundaries "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-04-28 16:00 -0700
                Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-04-29 05:52 +0200
                Re: speed of unaligned accesses that cross page-boundaries "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-05-04 18:06 -0700
                Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-05-05 06:13 +0200
                Re: speed of unaligned accesses that cross page-boundaries "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-05-04 21:27 -0700
                Re: speed of unaligned accesses that cross page-boundaries Bonita Montero <Bonita.Montero@gmail.com> - 2022-05-05 07:37 +0200
                Re: speed of unaligned accesses that cross page-boundaries Öö Tiib <ootiib@hot.ee> - 2022-05-05 04:34 -0700
                Re: speed of unaligned accesses that cross page-boundaries "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-05-05 12:16 -0700

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