[Top] [All Lists]

Re: 64-bit and N32 kernel interfaces

To: (Maciej W. Rozycki)
Subject: Re: 64-bit and N32 kernel interfaces
From: Hartvig Ekner <>
Date: Thu, 5 Sep 2002 20:07:03 +0200 (CEST)
Cc: (Daniel Jacobowitz), (Hartvig Ekner), (Kevin D. Kissell), (Tor Arntsen), (Carsten Langgaard), (Ralf Baechle),
In-reply-to: <> from "Maciej W. Rozycki" at Sep 05, 2002 05:10:51
Original-recipient: rfc822;
Maciej W. Rozycki writes:
> On Thu, 5 Sep 2002, Daniel Jacobowitz wrote:
> > No - the point is that all data types have the same size in N32.  It
> > was created explicitly as a transitional sop for people who didn't want
> > to fix their code, but wanted a performance increase from their 64-bit
> > hardware.
>  Well, what's the performance increase of n32 over o32?  The increased
> number of argument registers?  I doubt it's noticeable in most cases.

The technical benefits of n32 over o32 are:

* More argument registers => less memory traffic, less D-cache use,
        => faster code

* 64-bit datapath of CPU can be utilized with big impact on certain

* 32 floating point registers instead of 16 (and more efficient
  parameter passing as well)


<Prev in Thread] Current Thread [Next in Thread>