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Re: [PATCH] normal_distribution<double> performance improvement with SSE

From: Ulrich Drepper <drepper at gmail dot com>
To: libstdc++ at gcc dot gnu dot org
Cc: Jakub Jelinek <jakub at redhat dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
Date: Wed, 26 Sep 2012 13:02:21 -0400
Subject: Re: [PATCH] normal_distribution<double> performance improvement with SSE
References: <CAOPLpQcrVcVN0yZtgY9P+m_YA8E3Efdh9QzG17dGyJ2-Tg2o3Q@mail.gmail.com> <20120926113206.GQ1787@tucnak.redhat.com> <CAOPLpQcCDZz1voQucfq=3S1ggjqBWwkB0YJgu2fH_X0bWbrzcQ@mail.gmail.com> <alpine.DEB.2.02.1209261753410.3773@laptop-mg.saclay.inria.fr>

On Wed, Sep 26, 2012 at 12:14 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
>> Currently the random number engine interface is
>> inefficient since it returns a single number.  What we need is an
>> additional interface to return vectors.
>
>
> Isn't the __generate interface good enough?

__generate is for the distributions.  I'm talking about the engines.
Bulk access isn't that easy there.  The stream is deterministic and if
I request 32 bytes of entropy although I only need 16 bytes I cannot
push back the remaining 16 bytes.  Without that the next use of the
engine would produce different bits.

References:
- [PATCH] normal_distribution<double> performance improvement with SSE
  - From: Ulrich Drepper
- Re: [PATCH] normal_distribution<double> performance improvement with SSE
  - From: Jakub Jelinek
- Re: [PATCH] normal_distribution<double> performance improvement with SSE
  - From: Ulrich Drepper
- Re: [PATCH] normal_distribution<double> performance improvement with SSE
  - From: Marc Glisse

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