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Re: (un)aligned accesses on x86 platform.

From: Piotr Wyderski <piotr dot wyderski at gmail dot com>
To: Alexey Salmin <alexey dot salmin at gmail dot com>
Cc: Tristan Gingold <gingold at adacore dot com>, "H.J. Lu" <hjl dot tools at gmail dot com>, PaweÅ Sikora <pluto at agmk dot net>, gcc at gcc dot gnu dot org
Date: Tue, 16 Mar 2010 17:16:04 +0100
Subject: Re: (un)aligned accesses on x86 platform.
References: <op.u889o5kpzu3k57@pawels.alatek.krakow.pl> <6dc9ffc81003160750ge5ec0a3l8cda117216bbb102@mail.gmail.com> <170A1D5F-CF9E-405F-9056-3D23FBE9F130@adacore.com> <87a8dc11003160837u14c2fdfenef62c73c851344ce@mail.gmail.com> <ED71540A-9DDE-4738-99AB-2EEB2A4E8844@adacore.com> <87a8dc11003160904p678114cbj9522a62613f184f9@mail.gmail.com>

Alexey Salmin wrote:

> I always thought that unaligned access is much slower than aligned one.

It is not *MUCH* slower, just slower (unless you cross cache line
boundary). Unaligned accesses are very useful for improving
performance of, among other things, certain hash functions (e.g. Paul
Hsieh's one).

Best regards,
Piotr Wyderski

References:
- (un)aligned accesses on x86 platform.
  - From: PaweÅ Sikora
- Re: (un)aligned accesses on x86 platform.
  - From: H.J. Lu
- Re: (un)aligned accesses on x86 platform.
  - From: Tristan Gingold
- Re: (un)aligned accesses on x86 platform.
  - From: Alexey Salmin
- Re: (un)aligned accesses on x86 platform.
  - From: Tristan Gingold
- Re: (un)aligned accesses on x86 platform.
  - From: Alexey Salmin

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