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Re: problem about dma

To: wuming <wuming@ict.ac.cn>
Subject: Re: problem about dma
From: Fuxin Zhang <fxzhang@ict.ac.cn>
Date: Mon, 20 Dec 2004 21:14:16 +0800
Cc: linux-mips@linux-mips.org
In-reply-to: <002101c4e679$72938bc0$6f64a8c0@spark>
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References: <001501c4e646$7f676c00$6f64a8c0@spark> <41C690CF.2010306@niisi.msk.ru> <002101c4e679$72938bc0$6f64a8c0@spark>
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I think that speculative loads may be the answer.
wuming wrote:

----- Original Message ----- From: "Gleb O. Raiko" <raiko@niisi.msk.ru>
To: "wuming" <wuming@ict.ac.cn>
Cc: <linux-mips@linux-mips.org>
Sent: Monday, December 20, 2004 4:43 PM
Subject: Re: problem about dma


In 2.4, memcpy's prefetch may (and, in practice, do, no smiles, it cost me a lot of time to realize) access that memory. I though it has been fixed in 2.6 someday.

Regards,
Gleb.

Thank you! :)
But I think it is not the only reason, because the CPU on my platform does not support the "pref" instruction. So, memcpy's prefetch may have no effect on that arrange of memory.


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