From: "Gérard Roudier" <groudier@free.fr>
To: Josh Fryman <fryman@cc.gatech.edu>
Cc: Linus Torvalds <torvalds@transmeta.com>, <pavel@suse.cz>,
<linux-kernel@vger.kernel.org>
Subject: Re: 2.4.14-pre6
Date: Mon, 5 Nov 2001 20:04:33 +0100 (CET) [thread overview]
Message-ID: <20011105195626.T2092-100000@gerard> (raw)
In-Reply-To: <20011105162753.626cbdb6.fryman@cc.gatech.edu>
On Mon, 5 Nov 2001, Josh Fryman wrote:
> > Basically, you get two virtual CPU's per die, and each CPU can run two
> > threads at the same time. It slows some stuff down, because it makes for
> > much more cache pressure, but Intel claims up to 30% improvement on some
> > loads that scale well.
> >
> > The 30% is probably a marketing number (ie it might be more like 10% on
> > more normal loads), but you have to give them points for interesting
> > technology <)
>
> Specifically, the 30% comes in two places. Using Intel proprietary
> benchmarks (unreleased, according to the footnotes) they find that a
> typical IA32 instruction mix uses some 35% of system resources in an
> advanced device like the P4 with NetBurst. the rest is idle.
>
> by using the SMT model with two virtual systems - each with complete
> register sets and independent APICs, sharing only the backend exec
> units - they claim you get a 30% improvement in wall-clock time. This
> is supposed to be on their benchmarks *without* recompiling anything. To
> get "additional" improvement, using code to take advantage of the dual
> virtual CPUs nature of the chip and recompiling should give some
> unquantified gain.
All things being equal, this probably will make a NxMHz P4 be as fast as a
NxMHz PIII. But the new complexity it may require in real life may just
turn the gain into just nil.
What a great improvement, indeed! :-)
Gérard.
next prev parent reply other threads:[~2001-11-05 21:49 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-10-31 8:00 2.4.14-pre6 Linus Torvalds
2001-10-31 9:10 ` 2.4.14-pre6 Andrew Morton
2001-10-31 9:29 ` 2.4.14-pre6 Jens Axboe
2001-10-31 9:30 ` 2.4.14-pre6 bert hubert
2001-10-31 19:27 ` 2.4.14-pre6 Michael Peddemors
2001-10-31 19:38 ` 2.4.14-pre6 Linus Torvalds
2001-10-31 19:55 ` 2.4.14-pre6 Mike Castle
2001-10-31 20:02 ` 2.4.14-pre6 Rik van Riel
2001-10-31 23:18 ` 2.4.14-pre6 Erik Andersen
2001-10-31 23:40 ` 2.4.14-pre6 Dax Kelson
2001-10-31 23:57 ` 2.4.14-pre6 Michael Peddemors
2001-10-31 19:52 ` 2.4.14-pre6 Philipp Matthias Hahn
2001-10-31 21:05 ` 2.4.14-pre6 H. Peter Anvin
2001-11-01 19:14 ` 2.4.14-pre6 Pozsar Balazs
2001-11-02 12:01 ` 2.4.14-pre6 Pavel Machek
2001-11-05 20:43 ` 2.4.14-pre6 Charles Cazabon
2001-11-05 20:49 ` 2.4.14-pre6 Linus Torvalds
2001-11-05 21:04 ` 2.4.14-pre6 Johannes Erdfelt
2001-11-05 21:08 ` 2.4.14-pre6 Wilson
2001-11-05 21:27 ` 2.4.14-pre6 Josh Fryman
2001-11-05 19:04 ` Gérard Roudier [this message]
2001-11-02 16:48 ` 2.4.14-pre6 jogi
2001-11-03 12:47 ` 2.4.14-pre6 Mike Galbraith
2001-11-03 18:01 ` 2.4.14-pre6 Linus Torvalds
2001-11-03 19:07 ` 2.4.14-pre6 Mike Galbraith
2001-10-31 16:15 2.4.14-pre6 Linus Torvalds
2001-10-31 18:36 ` 2.4.14-pre6 Andrew Morton
2001-10-31 19:06 ` 2.4.14-pre6 Linus Torvalds
2001-11-01 10:20 ` 2.4.14-pre6 Neil Brown
2001-11-01 20:55 ` 2.4.14-pre6 Andrew Morton
2001-11-02 8:00 ` 2.4.14-pre6 Helge Hafting
2001-11-04 22:34 ` 2.4.14-pre6 Pavel Machek
2001-11-04 23:16 ` 2.4.14-pre6 Daniel Phillips
2001-11-01 21:28 ` 2.4.14-pre6 Chris Mason
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