From: "Kevin D. Kissell" <kevink@mips.com>
To: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
Cc: <linux-mips@linux-mips.org>
Subject: Re: Promblem with PREF (prefetching) in memcpy
Date: Fri, 4 Oct 2002 16:17:01 +0200 [thread overview]
Message-ID: <016201c26bb0$b8609a30$10eca8c0@grendel> (raw)
In-Reply-To: 1033739046.31861.35.camel@irongate.swansea.linux.org.uk
From: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
> On Fri, 2002-10-04 at 14:15, Kevin D. Kissell wrote:
> > Which is excatly the point that Carsten was raising when he started this thread!
> >
> > The question is how, i.e. throttle memcpy or thow away a "guard band" of RAM?
>
>
> The x86 code basically says
>
> while(over 320 bytes left)
> {
> prefetch ahead
> copy bits
> }
> while(bytes left)
> copy bits
Which is safe, simple, and efficient, but does seem to have the property
that there's a "cursed" page in the system that can be randomly allocated
and which will be curiously slow on memcopy(). That might or might not
be a problem in the embedded application space.
Regards,
Kevin K.
WARNING: multiple messages have this Message-ID (diff)
From: "Kevin D. Kissell" <kevink@mips.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: linux-mips@linux-mips.org
Subject: Re: Promblem with PREF (prefetching) in memcpy
Date: Fri, 4 Oct 2002 16:17:01 +0200 [thread overview]
Message-ID: <016201c26bb0$b8609a30$10eca8c0@grendel> (raw)
Message-ID: <20021004141701.IwkMaMn9OX6Qq_Obghrp7X0j5pqGyncr_P1s21SEW1s@z> (raw)
In-Reply-To: 1033739046.31861.35.camel@irongate.swansea.linux.org.uk
From: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
> On Fri, 2002-10-04 at 14:15, Kevin D. Kissell wrote:
> > Which is excatly the point that Carsten was raising when he started this thread!
> >
> > The question is how, i.e. throttle memcpy or thow away a "guard band" of RAM?
>
>
> The x86 code basically says
>
> while(over 320 bytes left)
> {
> prefetch ahead
> copy bits
> }
> while(bytes left)
> copy bits
Which is safe, simple, and efficient, but does seem to have the property
that there's a "cursed" page in the system that can be randomly allocated
and which will be curiously slow on memcopy(). That might or might not
be a problem in the embedded application space.
Regards,
Kevin K.
next prev parent reply other threads:[~2002-10-04 14:14 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-04 7:50 Promblem with PREF (prefetching) in memcpy Carsten Langgaard
2002-10-04 11:53 ` Dominic Sweetman
2002-10-04 12:11 ` Carsten Langgaard
2002-10-04 12:35 ` Dr. David Alan Gilbert
2002-10-04 12:36 ` Alan Cox
2002-10-04 12:35 ` Carsten Langgaard
2002-10-04 13:09 ` Alan Cox
2002-10-04 13:07 ` Hartvig Ekner
2002-10-04 13:07 ` Hartvig Ekner
2002-10-04 13:00 ` Kevin D. Kissell
2002-10-04 13:00 ` Kevin D. Kissell
2002-10-04 13:15 ` Alan Cox
2002-10-04 13:15 ` Kevin D. Kissell
2002-10-04 13:15 ` Kevin D. Kissell
2002-10-04 13:44 ` Alan Cox
2002-10-04 14:17 ` Kevin D. Kissell [this message]
2002-10-04 14:17 ` Kevin D. Kissell
2002-10-04 14:54 ` Alan Cox
2002-10-04 13:01 ` Maciej W. Rozycki
2002-10-04 13:17 ` Ralf Baechle
2002-10-04 13:32 ` Maciej W. Rozycki
2002-10-04 13:29 ` Dominic Sweetman
2002-10-04 13:46 ` Maciej W. Rozycki
2002-10-04 12:33 ` Hartvig Ekner
2002-10-04 12:33 ` Hartvig Ekner
2002-10-04 12:38 ` Ralf Baechle
2002-10-04 12:36 ` Kevin D. Kissell
2002-10-04 12:36 ` Kevin D. Kissell
2002-10-04 14:24 ` Dominic Sweetman
2002-10-04 14:24 ` Dominic Sweetman
2002-10-04 23:43 ` Ralf Baechle
2002-10-05 15:12 ` Hartvig Ekner
2002-10-05 15:12 ` Hartvig Ekner
2002-10-05 15:56 ` Alan Cox
2002-10-04 12:37 ` Kevin D. Kissell
2002-10-04 12:37 ` Kevin D. Kissell
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