Message-ID: <4385DB32.7010605@argo.co.il>
Date: Thu, 24 Nov 2005 17:24:34 +0200
From: Avi Kivity <avi@argo.co.il>
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To: Andi Kleen <ak@suse.de>
CC: Benjamin LaHaise <bcrl@kvack.org>, Jeff Garzik <jgarzik@pobox.com>,
       Andrew Grover <andrew.grover@intel.com>, netdev@vger.kernel.org,
       linux-kernel@vger.kernel.org, john.ronciak@intel.com,
       christopher.leech@intel.com
Subject: Re: [RFC] [PATCH 0/3] ioat: DMA engine support
References: <Pine.LNX.4.44.0511231143380.32487-100000@isotope.jf.intel.com> <4384E7F2.2030508@pobox.com> <20051123223007.GA5921@wotan.suse.de> <20051124001700.GC14246@kvack.org> <20051124065037.GZ20775@brahms.suse.de>
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Andi Kleen wrote:

>>Don't forget that there are benefits of not polluting the cache with the 
>>traffic for the incoming skbs.
>>    
>>
>
>Is that a general benefit outside benchmarks? I would expect
>most real programs to actually do something with the data
>- and that usually involves needing it in cache.
>
>  
>
As an example, an NFS server reads some data pages using iSCSI and sends 
them using NFS/TCP (or vice versa).

>>In the I/O AT case it might make sense to do a few prefetch()es of the 
>>userland data on the return-to-userspace code path.  
>>    
>>
>
>Some prefetches for user space might be a good idea yes
>
>  
>
As long as they can be turned off. Not all usespace applications want to 
touch the data immediately.


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