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From: hpa@zytor.com (H. Peter Anvin)
To: linux-kernel@vger.kernel.org
Subject: Re: AES assembler optimizations
Date: Tue, 10 Aug 2004 19:51:29 +0000 (UTC)	[thread overview]
Message-ID: <cfb901$ctg$1@terminus.zytor.com> (raw)
In-Reply-To: 20040809171231.GG2716@mea-ext.zmailer.org

Followup to:  <20040809171231.GG2716@mea-ext.zmailer.org>
By author:    Matti Aarnio <matti.aarnio@zmailer.org>
In newsgroup: linux.dev.kernel
> 
> Usage of MMX inside the Linux kernel is like the usage of FP inside
> the Linux kernel:  Can be done after jumping complex hoops, BUT NOT
> RECOMMENDED... (MMX in intertwined with FP hardware, after all.)
> 
> You have to do lots of the MMXes in order to win after amortizing those
> necessary hoops...  RAID-5 code does XOR via MMX code, under some 
> conditions.  ... where that happens to become a win.
> 

It's not really that hard, you just have to have enough work to
amortize it over.  The two metrics are: how much work do you get per
call, and how much work do you get before the next schedule().

	-hpa

  reply	other threads:[~2004-08-10 19:51 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <2riR3-7U5-3@gated-at.bofh.it>
2004-08-09 14:28 ` AES assembler optimizations Andi Kleen
2004-08-09 16:02   ` Bob Deblier
2004-08-09 17:12     ` Matti Aarnio
2004-08-10 19:51       ` H. Peter Anvin [this message]
2004-08-10 20:36         ` David S. Miller
2004-08-11  1:02           ` Paul Mackerras
2004-08-11  1:25             ` David S. Miller
2004-08-12 20:18           ` Bill Davidsen
2004-08-09 18:16     ` Andi Kleen
2004-08-09 20:20     ` dean gaudet
2004-08-09 13:47 Bob Deblier
2004-08-09 14:32 ` Patrick McFarland

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